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[PATCH OLK-6.6] apparmor: fix deadlock in complain-mode change_hat
by Gaosheng Cui 28 Sep '26

28 Sep '26

From: John Johansen <john.johansen(a)canonical.com> mainline inclusion from mainline-v7.3-rc1 commit 4ec11f14d1d6fdda787d991b142537be7841d395 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19429 CVE: CVE-2026-90179 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -------------------------------- The use of change_hat when in complain mode can cause a deadlock when the hat doesn't exist and a new learning profile is created for the missing profile. This is because change_hat() has taken the lock to search the hat list and creating the new learning profile needs to take the lock to add it to the list. From the bug report: Originally found in 7.0.0 in LTS ubuntu 26.04 with pam_apparmor + su in complain mode set to change hats. Then verified in newest available vanilla kernel I've compiled to see if still present: 7.2-rc7 vanilla -> affected checked also some other kernels: 6.18.44 vanilla -> affected 6.12.95 with debian patches -> unaffected On systems without bug (for example 6.12.95 debian) it just prints: aa_change_hat rc=0 On systems with bug, the executable always hangs, prints nothing and becomes unkillable. (And once stuck this way, it will cause any further hat changes to also cause the changing process to get stuck) Then in syslog you can find hint about cause: kernel: INFO: task hat:3409 blocked for more than 483 seconds. kernel: Not tainted 7.2.0-rc7 #1 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: task:hat state:D stack:0 pid:3409 tgid:3409 ppid:2605 task_flags:0x400000 flags:0x00080800 kernel: Call Trace: kernel: <TASK> kernel: __schedule+0x48f/0xfe0 kernel: schedule+0x27/0xa0 kernel: schedule_preempt_disabled+0x15/0x30 kernel: __mutex_lock.constprop.0+0x569/0xa10 kernel: aa_new_learning_profile+0x15f/0x210 kernel: build_change_hat+0x19f/0x3b0 kernel: change_hat.isra.0+0x5dd/0xd60 kernel: aa_change_hat+0x2f3/0x710 kernel: aa_setprocattr_changehat+0x121/0x1f0 kernel: do_setattr+0x28c/0x340 kernel: apparmor_setselfattr+0x20/0x50 kernel: security_setselfattr+0xf6/0x110 kernel: __x64_sys_lsm_set_self_attr+0x53/0x90 kernel: do_syscall_64+0xdd/0x5e0 kernel: ? __mod_memcg_lruvec_state+0xfd/0x260 kernel: ? lruvec_stat_mod_folio+0x8d/0xd0 kernel: ? __folio_mod_stat+0x2d/0x90 kernel: ? map_anon_folio_pte_nopf+0xd1/0x1f0 kernel: ? do_anonymous_page+0x184/0xa10 kernel: ? __handle_mm_fault+0x805/0x870 kernel: ? count_memcg_events+0xef/0x230 kernel: ? handle_mm_fault+0x1f0/0x2f0 kernel: ? do_user_addr_fault+0x2bb/0x7b0 kernel: ? do_syscall_64+0x94/0x5e0 kernel: ? exc_page_fault+0x75/0x160 kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e kernel: RIP: 0033:0x7f815e134c8d kernel: RSP: 002b:00007fff6df94ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000001cc kernel: RAX: ffffffffffffffda RBX: 0000556d8c81d040 RCX: 00007f815e134c8d kernel: RDX: 0000000000000046 RSI: 0000556d8c81d040 RDI: 0000000000000064 kernel: RBP: 00007fff6df94ef0 R08: 00007f815e212ac8 R09: 000000000000000c kernel: R10: 0000000000000000 R11: 0000000000000246 R12: 0000556d8c81d010 kernel: R13: 0000000000000026 R14: 0000000000000046 R15: 0000000000000064 kernel: </TASK> kernel: INFO: task hat:3409 is blocked on a mutex likely owned by task hat:3409. To fix the issue, lift the locking out of the core of aa_new_learning_profile(), introduce a wrapper function that takes the lock where needed, and have build_change_hat() call the core function that no longer takes the lock. In addition fix 4 other issues introduced by commit 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") - aa_get_profile_rcu() was replaced-by: aa_get_profile without the accompanying rcu_dereference_protected() - an extra aa_get_label(label) was introduced at the start of change_hat() without an accompanying aa_put_label() causing a reference count leak. - a reference count leak was introduced in the label_is_stale(label) case, where the newest profile would be leaked instead of the label passed to the function. - a potential UAF when the lookup walks up the tree with new_ns != ns the new label reference is put, and then used for the next lookup. The mutex_lock, will block replacement, and removal in the locked ns. However there are two cases where putting the reference can result in the label being freed even with the lock held. 1. the label does not have a list reference (possible for temporary or special profiles) in which case the put can trigger the cleanup. 2. the new label reference is in a different namespace, which does not have a lock held on it. This extends case 1 to also include replacement, and removal that could be occurring in the namespace new is in. Reported-by: Martin Petricek <mp(a)petricek.net> Link: https://lists.ubuntu.com/archives/apparmor/2026-August/014907.html Fixes: 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") Signed-off-by: John Johansen <john.johansen(a)canonical.com> Conflicts: security/apparmor/domain.c security/apparmor/policy.c [1)Context lines differ: hulk-6.6 uses label_for_each_in_ns rather than label_for_each_in_scope and the build path lacks the AA_BUG and blank line, both from mainline commits not backported; the needput put was placed directly between mutex_unlock and return. 2)Context lines differ: hulk-6.6 __aa_new_learning_profile has different local variables (no name_sz, uses kmalloc/sprintf rather than snprintf) from mainline commits not backported; only the mutex_is_locked assertion was added] Signed-off-by: Gaosheng Cui <cuigaosheng1(a)huawei.com> --- security/apparmor/domain.c | 25 +++++++++++++++++-------- security/apparmor/include/policy.h | 3 +++ security/apparmor/policy.c | 22 +++++++++++++++++----- 3 files changed, 37 insertions(+), 13 deletions(-) diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 0a4dd74c3050..4e0081cfd648 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -1029,8 +1029,8 @@ static struct aa_label *build_change_hat(const struct cred *subj_cred, if (!hat) { error = -ENOENT; if (COMPLAIN_MODE(profile)) { - hat = aa_new_learning_profile(profile, true, name, - GFP_KERNEL); + hat = __aa_new_learning_profile(profile, true, name, + GFP_KERNEL); if (!hat) { info = "failed null profile create"; error = -ENOMEM; @@ -1068,6 +1068,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, bool sibling = false; const char *name, *info = NULL; int i, error; + bool needput = false; AA_BUG(!label); AA_BUG(!hats); @@ -1080,7 +1081,6 @@ static struct aa_label *change_hat(const struct cred *subj_cred, * the profiles and label, we can rely on the namespaces being live * and avoid incrementing their refcounts while grabbing the lock. */ - label = aa_get_label(label); ns = labels_ns(label); retry: @@ -1088,15 +1088,19 @@ static struct aa_label *change_hat(const struct cred *subj_cred, if (label_is_stale(label)) { new = aa_get_newest_label(label); new_ns = labels_ns(new); + + if (needput) + /* aa_put_label() is safe to call when under lock */ + aa_put_label(label); + label = new; + needput = true; + /* check if replaced with label in parent ns, and lock there */ if (new_ns != ns) { - aa_put_label(new); mutex_unlock(&ns->lock); ns = new_ns; - label = new; + /* retry will bottom out at the root of the tree */ goto retry; } - aa_put_label(label); - label = new; } if (PROFILE_IS_HAT(labels_profile(label))) @@ -1107,7 +1111,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, name = hats[i]; label_for_each_in_ns(it, labels_ns(label), label, profile) { if (sibling && PROFILE_IS_HAT(profile)) { - root = aa_get_profile(profile->parent); + root = aa_get_profile(rcu_dereference_protected(profile->parent, + mutex_is_locked(&ns->lock))); } else if (!sibling && !PROFILE_IS_HAT(profile)) { root = aa_get_profile(profile); } else { /* conflicting change type */ @@ -1168,6 +1173,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, } } mutex_unlock(&ns->lock); + if (needput) + aa_put_label(label); return ERR_PTR(error); build: @@ -1181,6 +1188,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, goto fail; } /* else if (IS_ERR) build_change_hat has logged error so return new */ mutex_unlock(&ns->lock); + if (needput) + aa_put_label(label); return new; } diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h index 98dab531fe26..d0bf70669596 100644 --- a/security/apparmor/include/policy.h +++ b/security/apparmor/include/policy.h @@ -236,6 +236,9 @@ struct aa_profile *aa_alloc_profile(const char *name, struct aa_proxy *proxy, gfp_t gfp); struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, gfp_t gfp); +struct aa_profile *__aa_new_learning_profile(struct aa_profile *parent, + bool hat, const char *base, + gfp_t gfp); struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, const char *base, gfp_t gfp); void aa_free_profile(struct aa_profile *profile); diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index 0c6e255cb0a4..c917b29f83dd 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -642,7 +642,7 @@ struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, } /** - * aa_new_learning_profile - create or find a null-X learning profile + * __aa_new_learning_profile - create or find a null-X learning profile * @parent: profile that caused this profile to be created (NOT NULL) * @hat: true if the null- learning profile is a hat * @base: name to base the null profile off of @@ -659,14 +659,16 @@ struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, * * Returns: new refcounted profile else NULL on failure */ -struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, - const char *base, gfp_t gfp) +struct aa_profile *__aa_new_learning_profile(struct aa_profile *parent, + bool hat, const char *base, + gfp_t gfp) { struct aa_profile *p, *profile; const char *bname; char *name = NULL; AA_BUG(!parent); + AA_BUG(!mutex_is_locked(&parent->ns->lock)); if (base) { name = kmalloc(strlen(parent->base.hname) + 8 + strlen(base), @@ -698,7 +700,6 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, if (hat) profile->label.flags |= FLAG_HAT; - mutex_lock_nested(&profile->ns->lock, profile->ns->level); p = __find_child(&parent->base.profiles, bname); if (p) { aa_free_profile(profile); @@ -706,7 +707,6 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, } else { __add_profile(&parent->base.profiles, profile); } - mutex_unlock(&profile->ns->lock); /* refcount released by caller */ out: @@ -720,6 +720,18 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, return NULL; } +struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, + const char *base, gfp_t gfp) +{ + struct aa_profile *profile; + + mutex_lock_nested(&parent->ns->lock, parent->ns->level); + profile = __aa_new_learning_profile(parent, hat, base, gfp); + mutex_unlock(&parent->ns->lock); + + return profile; +} + /** * replacement_allowed - test to see if replacement is allowed * @profile: profile to test if it can be replaced (MAYBE NULL) -- 2.43.0

2 1

[PATCH OLK-5.10 0/3] CVE-2026-74668
by JiangJieHua 28 Sep '26

28 Sep '26

Qihang Tang (2): packet: use consistent hard_header_len in non-ring send paths packet: use consistent hard_header_len in TX_RING send path Yun Lu (1): af_packet: fix the SO_SNDTIMEO constraint not effective on tpacked_snd() include/linux/netdevice.h | 6 +++-- net/packet/af_packet.c | 49 +++++++++++++++++++++++---------------- 2 files changed, 33 insertions(+), 22 deletions(-) -- 2.33.8

2 4

[PATCH OLK-6.6] apparmor: fix deadlock in complain-mode change_hat
by Gaosheng Cui 28 Sep '26

28 Sep '26

From: John Johansen <john.johansen(a)canonical.com> mainline inclusion from mainline-v7.3-rc1 commit 4ec11f14d1d6fdda787d991b142537be7841d395 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19429 CVE: CVE-2026-90179 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -------------------------------- The use of change_hat when in complain mode can cause a deadlock when the hat doesn't exist and a new learning profile is created for the missing profile. This is because change_hat() has taken the lock to search the hat list and creating the new learning profile needs to take the lock to add it to the list. From the bug report: Originally found in 7.0.0 in LTS ubuntu 26.04 with pam_apparmor + su in complain mode set to change hats. Then verified in newest available vanilla kernel I've compiled to see if still present: 7.2-rc7 vanilla -> affected checked also some other kernels: 6.18.44 vanilla -> affected 6.12.95 with debian patches -> unaffected On systems without bug (for example 6.12.95 debian) it just prints: aa_change_hat rc=0 On systems with bug, the executable always hangs, prints nothing and becomes unkillable. (And once stuck this way, it will cause any further hat changes to also cause the changing process to get stuck) Then in syslog you can find hint about cause: kernel: INFO: task hat:3409 blocked for more than 483 seconds. kernel: Not tainted 7.2.0-rc7 #1 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: task:hat state:D stack:0 pid:3409 tgid:3409 ppid:2605 task_flags:0x400000 flags:0x00080800 kernel: Call Trace: kernel: <TASK> kernel: __schedule+0x48f/0xfe0 kernel: schedule+0x27/0xa0 kernel: schedule_preempt_disabled+0x15/0x30 kernel: __mutex_lock.constprop.0+0x569/0xa10 kernel: aa_new_learning_profile+0x15f/0x210 kernel: build_change_hat+0x19f/0x3b0 kernel: change_hat.isra.0+0x5dd/0xd60 kernel: aa_change_hat+0x2f3/0x710 kernel: aa_setprocattr_changehat+0x121/0x1f0 kernel: do_setattr+0x28c/0x340 kernel: apparmor_setselfattr+0x20/0x50 kernel: security_setselfattr+0xf6/0x110 kernel: __x64_sys_lsm_set_self_attr+0x53/0x90 kernel: do_syscall_64+0xdd/0x5e0 kernel: ? __mod_memcg_lruvec_state+0xfd/0x260 kernel: ? lruvec_stat_mod_folio+0x8d/0xd0 kernel: ? __folio_mod_stat+0x2d/0x90 kernel: ? map_anon_folio_pte_nopf+0xd1/0x1f0 kernel: ? do_anonymous_page+0x184/0xa10 kernel: ? __handle_mm_fault+0x805/0x870 kernel: ? count_memcg_events+0xef/0x230 kernel: ? handle_mm_fault+0x1f0/0x2f0 kernel: ? do_user_addr_fault+0x2bb/0x7b0 kernel: ? do_syscall_64+0x94/0x5e0 kernel: ? exc_page_fault+0x75/0x160 kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e kernel: RIP: 0033:0x7f815e134c8d kernel: RSP: 002b:00007fff6df94ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000001cc kernel: RAX: ffffffffffffffda RBX: 0000556d8c81d040 RCX: 00007f815e134c8d kernel: RDX: 0000000000000046 RSI: 0000556d8c81d040 RDI: 0000000000000064 kernel: RBP: 00007fff6df94ef0 R08: 00007f815e212ac8 R09: 000000000000000c kernel: R10: 0000000000000000 R11: 0000000000000246 R12: 0000556d8c81d010 kernel: R13: 0000000000000026 R14: 0000000000000046 R15: 0000000000000064 kernel: </TASK> kernel: INFO: task hat:3409 is blocked on a mutex likely owned by task hat:3409. To fix the issue, lift the locking out of the core of aa_new_learning_profile(), introduce a wrapper function that takes the lock where needed, and have build_change_hat() call the core function that no longer takes the lock. In addition fix 4 other issues introduced by commit 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") - aa_get_profile_rcu() was replaced-by: aa_get_profile without the accompanying rcu_dereference_protected() - an extra aa_get_label(label) was introduced at the start of change_hat() without an accompanying aa_put_label() causing a reference count leak. - a reference count leak was introduced in the label_is_stale(label) case, where the newest profile would be leaked instead of the label passed to the function. - a potential UAF when the lookup walks up the tree with new_ns != ns the new label reference is put, and then used for the next lookup. The mutex_lock, will block replacement, and removal in the locked ns. However there are two cases where putting the reference can result in the label being freed even with the lock held. 1. the label does not have a list reference (possible for temporary or special profiles) in which case the put can trigger the cleanup. 2. the new label reference is in a different namespace, which does not have a lock held on it. This extends case 1 to also include replacement, and removal that could be occurring in the namespace new is in. Reported-by: Martin Petricek <mp(a)petricek.net> Link: https://lists.ubuntu.com/archives/apparmor/2026-August/014907.html Fixes: 32e92764d6f8d ("apparmor: grab ns lock and refresh when looking up changehat child profiles") Signed-off-by: John Johansen <john.johansen(a)canonical.com> Conflicts: security/apparmor/domain.c security/apparmor/policy.c [1)Context lines differ: hulk-6.6 uses label_for_each_in_ns rather than label_for_each_in_scope and the build path lacks the AA_BUG and blank line, both from mainline commits not backported; the needput put was placed directly between mutex_unlock and return. 2)Context lines differ: hulk-6.6 __aa_new_learning_profile has different local variables (no name_sz, uses kmalloc/sprintf rather than snprintf) from mainline commits not backported; only the mutex_is_locked assertion was added] Signed-off-by: Gaosheng Cui <cuigaosheng1(a)huawei.com> --- security/apparmor/domain.c | 25 +++++++++++++++++-------- security/apparmor/include/policy.h | 3 +++ security/apparmor/policy.c | 22 +++++++++++++++++----- 3 files changed, 37 insertions(+), 13 deletions(-) diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 0a4dd74c3050..4e0081cfd648 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -1029,8 +1029,8 @@ static struct aa_label *build_change_hat(const struct cred *subj_cred, if (!hat) { error = -ENOENT; if (COMPLAIN_MODE(profile)) { - hat = aa_new_learning_profile(profile, true, name, - GFP_KERNEL); + hat = __aa_new_learning_profile(profile, true, name, + GFP_KERNEL); if (!hat) { info = "failed null profile create"; error = -ENOMEM; @@ -1068,6 +1068,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, bool sibling = false; const char *name, *info = NULL; int i, error; + bool needput = false; AA_BUG(!label); AA_BUG(!hats); @@ -1080,7 +1081,6 @@ static struct aa_label *change_hat(const struct cred *subj_cred, * the profiles and label, we can rely on the namespaces being live * and avoid incrementing their refcounts while grabbing the lock. */ - label = aa_get_label(label); ns = labels_ns(label); retry: @@ -1088,15 +1088,19 @@ static struct aa_label *change_hat(const struct cred *subj_cred, if (label_is_stale(label)) { new = aa_get_newest_label(label); new_ns = labels_ns(new); + + if (needput) + /* aa_put_label() is safe to call when under lock */ + aa_put_label(label); + label = new; + needput = true; + /* check if replaced with label in parent ns, and lock there */ if (new_ns != ns) { - aa_put_label(new); mutex_unlock(&ns->lock); ns = new_ns; - label = new; + /* retry will bottom out at the root of the tree */ goto retry; } - aa_put_label(label); - label = new; } if (PROFILE_IS_HAT(labels_profile(label))) @@ -1107,7 +1111,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, name = hats[i]; label_for_each_in_ns(it, labels_ns(label), label, profile) { if (sibling && PROFILE_IS_HAT(profile)) { - root = aa_get_profile(profile->parent); + root = aa_get_profile(rcu_dereference_protected(profile->parent, + mutex_is_locked(&ns->lock))); } else if (!sibling && !PROFILE_IS_HAT(profile)) { root = aa_get_profile(profile); } else { /* conflicting change type */ @@ -1168,6 +1173,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, } } mutex_unlock(&ns->lock); + if (needput) + aa_put_label(label); return ERR_PTR(error); build: @@ -1181,6 +1188,8 @@ static struct aa_label *change_hat(const struct cred *subj_cred, goto fail; } /* else if (IS_ERR) build_change_hat has logged error so return new */ mutex_unlock(&ns->lock); + if (needput) + aa_put_label(label); return new; } diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h index 98dab531fe26..d0bf70669596 100644 --- a/security/apparmor/include/policy.h +++ b/security/apparmor/include/policy.h @@ -236,6 +236,9 @@ struct aa_profile *aa_alloc_profile(const char *name, struct aa_proxy *proxy, gfp_t gfp); struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, gfp_t gfp); +struct aa_profile *__aa_new_learning_profile(struct aa_profile *parent, + bool hat, const char *base, + gfp_t gfp); struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, const char *base, gfp_t gfp); void aa_free_profile(struct aa_profile *profile); diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index 0c6e255cb0a4..c917b29f83dd 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -642,7 +642,7 @@ struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, } /** - * aa_new_learning_profile - create or find a null-X learning profile + * __aa_new_learning_profile - create or find a null-X learning profile * @parent: profile that caused this profile to be created (NOT NULL) * @hat: true if the null- learning profile is a hat * @base: name to base the null profile off of @@ -659,14 +659,16 @@ struct aa_profile *aa_alloc_null(struct aa_profile *parent, const char *name, * * Returns: new refcounted profile else NULL on failure */ -struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, - const char *base, gfp_t gfp) +struct aa_profile *__aa_new_learning_profile(struct aa_profile *parent, + bool hat, const char *base, + gfp_t gfp) { struct aa_profile *p, *profile; const char *bname; char *name = NULL; AA_BUG(!parent); + AA_BUG(!mutex_is_locked(&parent->ns->lock)); if (base) { name = kmalloc(strlen(parent->base.hname) + 8 + strlen(base), @@ -698,7 +700,6 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, if (hat) profile->label.flags |= FLAG_HAT; - mutex_lock_nested(&profile->ns->lock, profile->ns->level); p = __find_child(&parent->base.profiles, bname); if (p) { aa_free_profile(profile); @@ -706,7 +707,6 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, } else { __add_profile(&parent->base.profiles, profile); } - mutex_unlock(&profile->ns->lock); /* refcount released by caller */ out: @@ -720,6 +720,18 @@ struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, return NULL; } +struct aa_profile *aa_new_learning_profile(struct aa_profile *parent, bool hat, + const char *base, gfp_t gfp) +{ + struct aa_profile *profile; + + mutex_lock_nested(&parent->ns->lock, parent->ns->level); + profile = __aa_new_learning_profile(parent, hat, base, gfp); + mutex_unlock(&parent->ns->lock); + + return profile; +} + /** * replacement_allowed - test to see if replacement is allowed * @profile: profile to test if it can be replaced (MAYBE NULL) -- 2.43.0

1 0

[PATCH OLK-5.10] net: openvswitch: fix flow mask use-after-free on flow deletion
by Gaosheng Cui 28 Sep '26

28 Sep '26

From: Ilya Maximets <i.maximets(a)ovn.org> stable inclusion from stable-v5.10.270 commit ea5f7b45b582665541ddfb77dce98611354af4ab category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18828 CVE: CVE-2026-80994 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 4e30317ff67a2eb12b4d890d39f72fd7e7117d48 upstream. The commit in the Fixes tag below made so flow->mask free is scheduled via RCU right after it is removed from the flow table. The pointer stays in the flow structure and it can be accessible while in the same RCU critical section. This is done to avoid requiring ovs_mutex for the ovs_flow_free(). However, while removing the flow during processing of CMD_DEL, we do not take RCU read lock before the removal, and ovs_flow_cmd_fill_info() uses the flow->mask pointer afterwards. The RCU read lock is taken, but it's already late at that point. The comment on that line acknowledges that the lock is cosmetic and doesn't serve a real purpose. This leads to use-after-free if the RCU grace period passes between removal and the filling. It is a short race window, but it is there and can lead to a real crash in case memory allocation for the info takes a bit longer: BUG: KASAN: slab-use-after-free in __ovs_nla_put_key net/openvswitch/flow_netlink.c:1996 BUG: KASAN: slab-use-after-free in ovs_nla_put_key+0x2463/0x2e30 net/openvswitch/flow_netlink.c:2250 Read of size 4 at addr ffff88801ee89970 by task ovs_flow_del_ec/9487 Call Trace: <TASK> __ovs_nla_put_key net/openvswitch/flow_netlink.c:1996 ovs_nla_put_key+0x2463/0x2e30 net/openvswitch/flow_netlink.c:2250 ovs_flow_cmd_fill_info+0x420/0x9c0 net/openvswitch/datapath.c:930 ovs_flow_cmd_del+0x53a/0x970 net/openvswitch/datapath.c:1467 ... netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556 </TASK> Allocated by task 9487: mask_alloc net/openvswitch/flow_table.c:967 flow_mask_insert net/openvswitch/flow_table.c:1012 ovs_flow_tbl_insert+0xea2/0x1a90 net/openvswitch/flow_table.c:1084 ovs_flow_cmd_new+0x7e3/0xd90 net/openvswitch/datapath.c:1086 ... netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556 Freed by task 9485: rcu_free_sheaf+0x1e/0x100 mm/slub.c:5978 rcu_do_batch kernel/rcu/tree.c:2645 rcu_core+0x59c/0x10c0 kernel/rcu/tree.c:2897 handle_softirqs+0x1e4/0x9a0 kernel/softirq.c:622 ... instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 ovs_flow_tbl_remove() must be called after the ovs_flow_cmd_fill_info() to avoid this race. This also helps with cleaning up the forced cast and the cosmetic RCU read lock. Before the commit in the Fixes tag the order did not matter as long as the flow object itself was not freed. A wider RCU critical section could be another option, but we have a GFP_KERNEL allocation in the way. Reported by Trend Micro's Zero Day Initiative as ZDI-CAN-32042. Fixes: 56c19868e115 ("openvswitch: Make flow mask removal symmetric.") Cc: stable(a)vger.kernel.org Signed-off-by: Ilya Maximets <i.maximets(a)ovn.org> Reviewed-by: Aaron Conole <aconole(a)redhat.com> Link: https://patch.msgid.link/20260815005915.1097270-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Gaosheng Cui <cuigaosheng1(a)huawei.com> --- net/openvswitch/datapath.c | 45 +++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c index 529eb9d6acab..b6d5dddaf35d 100644 --- a/net/openvswitch/datapath.c +++ b/net/openvswitch/datapath.c @@ -1381,33 +1381,34 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct genl_info *info) goto unlock; } - ovs_flow_tbl_remove(&dp->table, flow); - ovs_unlock(); - - reply = ovs_flow_cmd_alloc_info((const struct sw_flow_actions __force *) flow->sf_acts, + reply = ovs_flow_cmd_alloc_info(ovsl_dereference(flow->sf_acts), &flow->id, info, false, ufid_flags); - if (likely(reply)) { - if (!IS_ERR(reply)) { - rcu_read_lock(); /*To keep RCU checker happy. */ - err = ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex, - reply, info->snd_portid, - info->snd_seq, 0, - OVS_FLOW_CMD_DEL, - ufid_flags); - rcu_read_unlock(); - if (WARN_ON_ONCE(err < 0)) { - kfree_skb(reply); - goto out_free; - } + if (IS_ERR(reply)) { + netlink_set_err(sock_net(skb->sk)->genl_sock, 0, 0, + PTR_ERR(reply)); + reply = NULL; + } - ovs_notify(&dp_flow_genl_family, reply, info); - } else { - netlink_set_err(sock_net(skb->sk)->genl_sock, 0, 0, - PTR_ERR(reply)); + if (likely(reply)) { + err = ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex, + reply, info->snd_portid, + info->snd_seq, 0, + OVS_FLOW_CMD_DEL, ufid_flags); + if (WARN_ON_ONCE(err < 0)) { + kfree_skb(reply); + reply = NULL; } } + /* Removal has to happen after ovs_flow_cmd_fill_info(), as it uses + * the flow->mask that can be scheduled to be freed by the + * ovs_flow_tbl_remove() and we're not holding the RCU read lock. + */ + ovs_flow_tbl_remove(&dp->table, flow); + ovs_unlock(); + + if (likely(reply)) + ovs_notify(&dp_flow_genl_family, reply, info); -out_free: ovs_flow_free(flow, true); return 0; unlock: -- 2.43.0

1 0

[PATCH OLK-6.6] md/raid5: round bitmap stripes with sector division
by Lu Jialin 28 Sep '26

28 Sep '26

From: Yu Kuai <yukuai(a)fygo.io> stable inclusion from stable-v6.6.157 commit 9d7490007707f90691911385365bd1d691d99225 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19461 CVE: CVE-2026-90279 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- [ Upstream commit 17ea021ae74987d6064c8195c4922fa025753892 ] raid5_bitmap_sector_map() aligns the array range to full RAID5 stripe widths before converting it to component sectors. That width is chunk_sectors multiplied by the number of data disks, and it is not always a power of two. Reproduce with a 4-disk RAID5, 1024-sector chunks, and three data disks. The full-stripe width is 3072 sectors. For a one-sector write at array sector 3072, correct rounding gives array range [3072, 6144), which maps to component range [1024, 2048). The old round_down()/round_up() logic instead gives [1024, 4096), which maps to [0, 1024). Use sector_div() based arithmetic so the rounded range is aligned to the actual RAID5 stripe width. The deterministic mapper test now reports the fixed component range as [1024, 2048), while the old mask-based range was [0, 1024). Fixes: 9c89f604476c ("md/raid5: implement pers->bitmap_sector()") Reported-by: Mykola Marzhan <mykola(a)meshstor.io> Link: https://lore.kernel.org/all/20260726185916.2223460-1-mykola@meshstor.io/ Tested-by: Mykola Marzhan <mykola(a)meshstor.io> Link: https://patch.msgid.link/20260802195038.164272-6-yukuai@kernel.org Signed-off-by: Yu Kuai <yukuai(a)fygo.io> Signed-off-by: Sasha Levin <sashal(a)kernel.org> Signed-off-by: Lu Jialin <lujialin4(a)huawei.com> --- drivers/md/raid5.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 6ec8e1b3d8b2..435612b60c53 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5899,8 +5899,11 @@ static void raid5_bitmap_sector(struct mddev *mddev, sector_t *offset, sectors_per_chunk = conf->chunk_sectors * (conf->raid_disks - conf->max_degraded); - start = round_down(start, sectors_per_chunk); - end = round_up(end, sectors_per_chunk); + sector_div(start, sectors_per_chunk); + start *= sectors_per_chunk; + if (sector_div(end, sectors_per_chunk)) + end++; + end *= sectors_per_chunk; start = raid5_compute_sector(conf, start, 0, &dd_idx, NULL); end = raid5_compute_sector(conf, end, 0, &dd_idx, NULL); @@ -5918,8 +5921,10 @@ static void raid5_bitmap_sector(struct mddev *mddev, sector_t *offset, sectors_per_chunk = conf->prev_chunk_sectors * (conf->previous_raid_disks - conf->max_degraded); - prev_start = round_down(prev_start, sectors_per_chunk); - prev_end = round_down(prev_end, sectors_per_chunk); + sector_div(prev_start, sectors_per_chunk); + prev_start *= sectors_per_chunk; + sector_div(prev_end, sectors_per_chunk); + prev_end *= sectors_per_chunk; prev_start = raid5_compute_sector(conf, prev_start, 1, &dd_idx, NULL); prev_end = raid5_compute_sector(conf, prev_end, 1, &dd_idx, NULL); -- 2.34.1

2 1

[PATCH OLK-6.6] mtd: rawnand: validate ONFI extended parameter page sections
by Lu Jialin 28 Sep '26

28 Sep '26

From: Pengpeng Hou <pengpeng(a)iscas.ac.cn> stable inclusion from stable-v6.6.157 commit ddb6ddf5be7429bb98b3368c883be51f00b31678 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19270 CVE: CVE-2026-89952 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit e5e415262330bd70f983e091d8919d9dcd99e475 upstream. nand_flash_detect_ext_param_page() allocates the length declared by the ONFI parameter page, then treats the data as a fixed header followed by variable-length sections. It reads that header and advances over sections without first proving that the fixed page and each current section fit in the allocation. Reject pages shorter than the fixed header, track the remaining variable area while walking sections, and require the ECC section to contain every field read from struct onfi_ext_ecc_info. Use device-scoped diagnostics that identify the malformed ONFI section. Fixes: 6dcbe0cdd83f ("mtd: get the ECC info from the Extended Parameter Page") Cc: stable(a)vger.kernel.org Signed-off-by: Pengpeng Hou <pengpeng(a)iscas.ac.cn> Signed-off-by: Miquel Raynal <miquel.raynal(a)bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Lu Jialin <lujialin4(a)huawei.com> --- drivers/mtd/nand/raw/nand_onfi.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c index 861975e44b55..f03553eb1324 100644 --- a/drivers/mtd/nand/raw/nand_onfi.c +++ b/drivers/mtd/nand/raw/nand_onfi.c @@ -35,16 +35,21 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, struct nand_onfi_params *p) { struct nand_device *base = &chip->base; + struct mtd_info *mtd = nand_to_mtd(chip); struct nand_ecc_props requirements; struct onfi_ext_param_page *ep; struct onfi_ext_section *s; struct onfi_ext_ecc_info *ecc; + size_t remaining, section_len; uint8_t *cursor; int ret; int len; int i; len = le16_to_cpu(p->ext_param_page_length) * 16; + if (len < sizeof(*ep)) + return -EINVAL; + ep = kmalloc(len, GFP_KERNEL); if (!ep) return -ENOMEM; @@ -77,11 +82,29 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, /* find the ECC section. */ cursor = (uint8_t *)(ep + 1); + remaining = len - sizeof(*ep); for (i = 0; i < ONFI_EXT_SECTION_MAX; i++) { s = ep->sections + i; - if (s->type == ONFI_SECTION_TYPE_2) + section_len = s->length * 16; + if (section_len > remaining) { + dev_dbg(&mtd->dev, + "ONFI extended parameter section %d exceeds page\n", + i); + goto ext_out; + } + + if (s->type == ONFI_SECTION_TYPE_2) { + if (section_len < sizeof(*ecc)) { + dev_dbg(&mtd->dev, + "ONFI extended parameter ECC section %d is too short\n", + i); + goto ext_out; + } break; - cursor += s->length * 16; + } + + cursor += section_len; + remaining -= section_len; } if (i == ONFI_EXT_SECTION_MAX) { pr_debug("We can not find the ECC section.\n"); -- 2.34.1

2 1

[PATCH OLK-6.6] ubi: Fix rollback for explicit UBI device numbers
by Lu Jialin 28 Sep '26

28 Sep '26

From: Yuho Choi <dbgh9129(a)gmail.com> stable inclusion from stable-v6.6.157 commit 552e565ed8846e7db143e4a6bdf3f5677453c686 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19443 CVE: CVE-2026-90216 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- [ Upstream commit 5b0a6b554e12a97f9771a9a9f4ea1f5457373c73 ] ubi_init_attach() rolls back module initialization failures by scanning ubi_devices[0..i-1], where i is the mtd= parameter index. That assumes the parameter index matches the UBI device number. That assumption is not true when mtd= specifies an explicit ubi_num. A successfully attached device can be stored at a higher ubi_devices[] slot, and a later failure can miss it during rollback. Scan the full ubi_devices[] array and detach by the actual array index, matching the way UBI devices are stored. Fixes: 83ff59a06663 ("UBI: support ubi_num on mtd.ubi command line") Signed-off-by: Yuho Choi <dbgh9129(a)gmail.com> Reviewed-by: Zhihao Cheng <chengzhihao1(a)huawei.com> Signed-off-by: Richard Weinberger <richard(a)nod.at> Signed-off-by: Sasha Levin <sashal(a)kernel.org> Signed-off-by: Lu Jialin <lujialin4(a)huawei.com> --- drivers/mtd/ubi/build.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c index 1a227c3b08b5..8c74020c8ce2 100644 --- a/drivers/mtd/ubi/build.c +++ b/drivers/mtd/ubi/build.c @@ -1316,10 +1316,10 @@ static int __init ubi_init(void) return 0; out_detach: - for (k = 0; k < i; k++) + for (k = 0; k < UBI_MAX_DEVICES; k++) if (ubi_devices[k]) { mutex_lock(&ubi_devices_mutex); - ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1); + ubi_detach_mtd_dev(k, 1); mutex_unlock(&ubi_devices_mutex); } ubi_debugfs_exit(); -- 2.34.1

1 0

[PATCH OLK-6.6] nvdimm/btt: reject an arena whose nfree is below the lane count
by Lu Jialin 28 Sep '26

28 Sep '26

From: Bryam Vargas <hexlabsecurity(a)proton.me> stable inclusion from stable-v6.6.157 commit f9bf05c63b77d000e9c01f3e47af36973887d350 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19097 CVE: CVE-2026-89965 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 6a1f2e5ed9267ca19187038ac635393c165213ac upstream. The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write. btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant. Fixes: 5212e11fde4d ("nd_btt: atomic sector updates") Cc: stable(a)vger.kernel.org Signed-off-by: Bryam Vargas <hexlabsecurity(a)proton.me> Reviewed-by: Alison Schofield <alison.schofield(a)intel.com> Tested-by: Alison Schofield <alison.schofield(a)intel.com> Link: https://patch.msgid.link/20260620-b4-disp-88b2514b-v1-1-3834e707d232@proton… Signed-off-by: Alison Schofield <alison.schofield(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Lu Jialin <lujialin4(a)huawei.com> --- drivers/nvdimm/btt.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c index 9e54083505f3..4cfed0a3d142 100644 --- a/drivers/nvdimm/btt.c +++ b/drivers/nvdimm/btt.c @@ -886,6 +886,14 @@ static int discover_arenas(struct btt *btt) arena->external_lba_start = cur_nlba; parse_arena_meta(arena, super, cur_off); + if (arena->nfree < btt->nd_region->num_lanes) { + dev_err(to_dev(arena), + "nfree %u smaller than lane count %d\n", + arena->nfree, btt->nd_region->num_lanes); + ret = -ENODEV; + goto out; + } + ret = log_set_indices(arena); if (ret) { dev_err(to_dev(arena), -- 2.34.1

2 1

[PATCH OLK-5.10] nvdimm/btt: reject an arena whose nfree is below the lane count
by Lu Jialin 28 Sep '26

28 Sep '26

From: Bryam Vargas <hexlabsecurity(a)proton.me> stable inclusion from stable-v5.10.270 commit eb491343d2d1784121ad9af91c25b338c28913c3 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19097 CVE: CVE-2026-89965 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 6a1f2e5ed9267ca19187038ac635393c165213ac upstream. The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write. btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant. Fixes: 5212e11fde4d ("nd_btt: atomic sector updates") Cc: stable(a)vger.kernel.org Signed-off-by: Bryam Vargas <hexlabsecurity(a)proton.me> Reviewed-by: Alison Schofield <alison.schofield(a)intel.com> Tested-by: Alison Schofield <alison.schofield(a)intel.com> Link: https://patch.msgid.link/20260620-b4-disp-88b2514b-v1-1-3834e707d232@proton… Signed-off-by: Alison Schofield <alison.schofield(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Lu Jialin <lujialin4(a)huawei.com> --- drivers/nvdimm/btt.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c index 12ff6f8784ac..45208cdd536a 100644 --- a/drivers/nvdimm/btt.c +++ b/drivers/nvdimm/btt.c @@ -886,6 +886,14 @@ static int discover_arenas(struct btt *btt) arena->external_lba_start = cur_nlba; parse_arena_meta(arena, super, cur_off); + if (arena->nfree < btt->nd_region->num_lanes) { + dev_err(to_dev(arena), + "nfree %u smaller than lane count %d\n", + arena->nfree, btt->nd_region->num_lanes); + ret = -ENODEV; + goto out; + } + ret = log_set_indices(arena); if (ret) { dev_err(to_dev(arena), -- 2.34.1

1 0

[PATCH OLK-6.6] mm/rmap: fix missing barrier between anon_vma init and vma->anon_vma publish
by Jinjiang Tu 28 Sep '26

28 Sep '26

mainline inclusion from mainline-v7.3-rc5 commit b6ac0b3f6013c168f22cad97e79967accacb08e1 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10048 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -------------------------------- On arm64 server, we find that a task trying to grab the anon_vma lock triggers hungtask. INFO: task main:2354726 blocked for more than 120 seconds. Tainted: G E 5.10.0-0021.aarch64 #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:main state:D stack: 0 pid:2354726 ppid:2350673 flags:0x00000a01 Call trace: __switch_to+0x7c/0xbc __schedule+0x3b4/0x8a0 schedule+0x50/0xe0 rwsem_down_write_slowpath+0x3cc/0x6cc down_write+0x60/0x260 __anon_vma_prepare+0x6c/0x210 do_anonymous_page+0x258/0x660 handle_pte_fault+0x188/0x214 __handle_mm_fault+0x1b0/0x380 handle_mm_fault+0xf4/0x284 do_page_fault+0x19c/0x494 do_translation_fault+0xcc/0xf8 do_mem_abort+0x48/0xac el0_da+0x44/0x80 el0_sync_handler+0x88/0xb4 el0_sync+0x160/0x180 After analyzing the vmcore, we found the anon_vma->root->rwsem.count is -1. There is another anon_vma whose anon_vma->root->rwsem.count is 1, the anon_vma->root->rwsem.owner shows the lock is held, but the stack of the task shows the task doesn't hold the anon_vma lock. After adding more debugging info, we found __anon_vma_prepare() reuses anon_vma and triggers the UAF of anon_vma->root due to missing memory barrier, leading to locking and unlocking two different anon_vma->root, thus leading to an anon_vma will never be unlocked, and another anon_vma couldn't be locked anymore. This race requires two adjacent VMAs that are not merged but are anon_vma-compatible (e.g., they differ in VMA_ACCESS_FLAGS that can be changed by mprotect()). Two threads fault on each VMA concurrently, both calling __anon_vma_prepare() with only mmap_lock held for reading. THREAD A THREAD B __anon_vma_prepare __anon_vma_prepare find_mergeable_anon_vma() -> NULL anon_vma = anon_vma_alloc(); anon_vma->root = anon_vma; // the two stores may be reordered vma->anon_vma = anon_vma; // finds A's anon_vma anon_vma = find_mergeable_anon_vma(vma); anon_vma_lock_write(anon_vma); // may still see the old root down_write(&anon_vma->root->rwsem); anon_vma_unlock_write(anon_vma); // see the new root, never unlock old up_write(&anon_vma->root->rwsem); thread A triggers page fault and calls __anon_vma_prepare() to prepare anon_vma for the faulting vma. __anon_vma_prepare() allocates and initializes a new anon_vma, and then publishes it to the vma with a plain store. anon_vma_prepare() only requires the mmap_lock to be held for reading, so two threads can fault on adjacent VMAs at the same time. While thread A publishes a new anon_vma, thread B could find the anon_vma via find_mergeable_anon_vma() and then locks anon_vma->root->rwsem. The store to anon_vma->root in anon_vma_alloc() and the store to vma->anon_vma can be reordered. The anon_vma_lock_write() and spin_lock() only provide acquire semantics, which do not prevent prior stores from being reordered after them. The release semantics of the corresponding spin_unlock() and anon_vma_unlock_write() come too late, the store to vma->anon_vma is already published before they take effect. As a result, thread B can observe the following order: vma->anon_vma = anon_vma; anon_vma->root = anon_vma; The anon_vma slab is SLAB_TYPESAFE_BY_RCU, so a newly allocated anon_vma may reuse memory from a previously freed one. The constructor (anon_vma_ctor) does not reset anon_vma->root, and __put_anon_vma() doesn't clear it either, so the old root value persists until anon_vma_alloc() overwrites it. If that store isn't visible, thread B reads a root that points to the old anon_vma and locks it. As a result, thread B can call anon_vma_lock_write() with the old root, and call anon_vma_unlock_write() with the new root, leading to an anon_vma will never be unlocked, and another anon_vma couldn't be locked anymore (its count is dropped from 0 to -1 due to wrong unlock). To fix it, change the plain store `vma->anon_vma = anon_vma` to store release, so that the fields of anon_vma are visible before anon_vma is published to vma->anon_vma. At read side, the load of anon_vma and anon_vma->root have address dependency. According to Documentation/memory-barriers.txt and some investigations, only Alpha needs address-dependency barriers and it has been handled by READ_ONCE() in reusable_anon_vma(). We reproduced this issue in v5.10 with KSM enabled. The kernel doesn't merge commit cf7e7a3503df ("mm: prevent KSM from breaking VMA merging for new VMAs"), so there are many adjacent VMAs that aren't merged but are compatible for anon_vma. Without this fix, our production environment could reproduce this issue about 2-5 times each month. After adding a smp_mb() before anon_vma_lock_write(anon_vma) in __anon_vma_prepare(), which is different to this patch, this issue hasn't been reproduced for one month. Link: https://lore.kernel.org/20260908122924.554373-1-tujinjiang@huawei.com Fixes: 5c341ee1dfc8 ("mm: track the root (oldest) anon_vma") Signed-off-by: Jinjiang Tu <tujinjiang(a)huawei.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> Reviewed-by: Lance Yang <lance.yang(a)linux.dev> Reviewed-by: Lorenzo Stoakes (ARM) <ljs(a)kernel.org> Acked-by: David Hildenbrand (Arm) <david(a)kernel.org> Acked-by: Vlastimil Babka (SUSE) <vbabka(a)kernel.org> Cc: Minchan Kim <minchan(a)kernel.org> Cc: Harry Yoo <harry(a)kernel.org> Cc: Hiroyouki Kamezawa <kamezawa.hiroyu(a)jp.fujitsu.com> Cc: Jann Horn <jannh(a)google.com> Cc: Jinjiang Tu <tujinjiang(a)huawei.com> Cc: Kefeng Wang <wangkefeng.wang(a)huawei.com> Cc: Larry Woodman <lwoodman(a)redhat.com> Cc: Liam R. Howlett <liam(a)infradead.org> Cc: Nanyong Sun <sunnanyong(a)huawei.com> Cc: Rik van Riel <riel(a)surriel.com> Cc: <stable(a)vger.kernel.org> Conflicts: mm/rmap.c mm/mmap.c mm/vma.c [Context conflicts.] Signed-off-by: Jinjiang Tu <tujinjiang(a)huawei.com> --- mm/mmap.c | 7 +++++++ mm/rmap.c | 6 +++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index 669bc1b74b35..7b0ba4395441 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1170,6 +1170,13 @@ static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct * * acceptable for merging, so we can do all of this optimistically. But * we do that READ_ONCE() to make sure that we never re-load the pointer. * + * The READ_ONCE() establishes an address dependency between anon_vma and + * any access to its fields, which pairs with the assignment to + * vma->anon_vma performed with release semantics in __anon_vma_prepare(). + * + * This is especially important as anon_vma's are SLAB_TYPESAFE_BY_RCU so + * accessing an uninitialised anon_vma's fields may result in a UAF. + * * IOW: that the "list_is_singular()" test on the anon_vma_chain only * matters for the 'stable anon_vma' case (ie the thing we want to avoid * is to return an anon_vma that is "complex" due to having gone through diff --git a/mm/rmap.c b/mm/rmap.c index ad0213898dcd..12718f5ed9d2 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -210,7 +210,11 @@ int __anon_vma_prepare(struct vm_area_struct *vma) /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); if (likely(!vma->anon_vma)) { - vma->anon_vma = anon_vma; + /* + * Make anon_vma fields visible before anon_vma is published. + * Paired with an address dependency in reusable_anon_vma(). + */ + smp_store_release(&vma->anon_vma, anon_vma); anon_vma_chain_link(vma, avc, anon_vma); anon_vma->num_active_vmas++; allocated = NULL; -- 2.43.0

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