- Kernel - mailweb.openeuler.org

[PATCH OLK-5.10 0/3] CVE-2026-64560
by Jinjie Ruan 03 Aug '26

03 Aug '26

CVE-2026-64560. Dan Carpenter (1): mm/slab: make __free(kfree) accept error pointers Peter Zijlstra (1): locking: Introduce __cleanup() based infrastructure Thomas Gleixner (1): posix-cpu-timers: Prevent UAF caused by non-leader exec() race drivers/dma/ioat/dma.c | 12 +- include/linux/cleanup.h | 171 +++++++++++++++++++++++++ include/linux/compiler-clang.h | 9 ++ include/linux/compiler_attributes.h | 6 + include/linux/device.h | 7 ++ include/linux/file.h | 6 + include/linux/irqflags.h | 7 ++ include/linux/mutex.h | 4 + include/linux/percpu.h | 4 + include/linux/preempt.h | 5 + include/linux/rcupdate.h | 3 + include/linux/rwsem.h | 9 ++ include/linux/sched/task.h | 2 + include/linux/slab.h | 4 +- include/linux/spinlock.h | 32 +++++ include/linux/srcu.h | 5 + kernel/exit.c | 8 +- kernel/signal.c | 10 +- kernel/time/posix-cpu-timers.c | 185 ++++++++++++++++++---------- scripts/checkpatch.pl | 2 +- 20 files changed, 417 insertions(+), 74 deletions(-) create mode 100644 include/linux/cleanup.h -- 2.34.1

2 4

[PATCH openEuler-1.0-LTS] hwrng: virtio: clamp device-reported used.len at copy_data()
by Chen Jinghuang 03 Aug '26

03 Aug '26

From: Michael Bommarito <michael.bommarito(a)gmail.com> mainline inclusion from mainline-v7.2-rc1 commit e3046eeada299f917a8ad883af4434bfb86556b1 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16747 CVE: CVE-2026-64456 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -------------------------------- random_recv_done() stores the device-reported used.len directly into vi->data_avail. copy_data() then indexes vi->data[] using vi->data_idx (advanced by previous copy_data() calls) and issues a memcpy() without re-validating either value against the posted buffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32 or 64). A malicious or buggy virtio-rng backend can set used.len beyond sizeof(vi->data), steering the memcpy() past the end of the inline array into adjacent kmalloc-1k slab bytes. hwrng_fillfn() mixes those bytes into the guest RNG, and guest root can also observe them directly via /dev/hwrng. Concrete impact is inside the guest: - Memory-safety / hardening: any virtio-rng backend that over-reports used.len causes the driver to read past vi->data into unrelated slab contents. hwrng_fillfn() is a kernel thread that runs as soon as the device is probed; no guest userspace interaction is required to first-trigger the OOB. - Cross-boundary leak (confidential-compute threat model): a malicious hypervisor cooperating with a malicious or compromised guest root userspace can use /dev/hwrng as a leak channel for guest-kernel heap data. The host sets a large used.len, guest root reads /dev/hwrng, and the returned bytes contain guest kernel slab contents that were adjacent to vi->data. In practice, confidential-compute guests (SEV-SNP, TDX) usually disable virtio-rng entirely, so this path is narrow, but the fix is still worth carrying because the underlying memory-safety bug contaminates the guest RNG on any host. KASAN confirms the OOB on a 7.1-rc4 guest whose virtio-rng backend has been patched to report used.len = 0x10000: BUG: KASAN: slab-out-of-bounds in virtio_read+0x394/0x5d0 Read of size 64 at addr ffff88800ae0ba20 by task hwrng/52 Call Trace: __asan_memcpy+0x23/0x60 virtio_read+0x394/0x5d0 hwrng_fillfn+0xb2/0x470 kthread+0x2cc/0x3a0 Allocated by task 1: probe_common+0xa5/0x660 virtio_dev_probe+0x549/0xbc0 The buggy address belongs to the object at ffff88800ae0b800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes to the right of allocated 544-byte region [ffff88800ae0b800, ffff88800ae0ba20) Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened usb9pfs_rx_complete() against unchecked device-reported length in the USB 9p transport. With the clamp at point of use and array_index_nospec() in place, the same harness boots cleanly: copy_data() returns zero for the bogus report, the device-supplied bytes after data_idx are discarded, and the driver issues a fresh request. Fixes: f7f510ec1957 ("virtio: An entropy device, as suggested by hpa.") Cc: stable(a)vger.kernel.org Suggested-by: Michael S. Tsirkin <mst(a)redhat.com> Signed-off-by: Michael Bommarito <michael.bommarito(a)gmail.com> Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael S. Tsirkin <mst(a)redhat.com> Message-ID: <20260531142251.2792061-1-michael.bommarito(a)gmail.com> Conflicts: drivers/char/hw_random/virtio-rng.c [context conflicts] Signed-off-by: Chen Jinghuang <chenjinghuang2(a)huawei.com> --- drivers/char/hw_random/virtio-rng.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 58884d875201..f4b695b33277 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -20,6 +20,7 @@ #include <asm/barrier.h> #include <linux/err.h> #include <linux/hw_random.h> +#include <linux/nospec.h> #include <linux/scatterlist.h> #include <linux/spinlock.h> #include <linux/virtio.h> @@ -78,8 +79,26 @@ static void request_entropy(struct virtrng_info *vi) static unsigned int copy_data(struct virtrng_info *vi, void *buf, unsigned int size) { - size = min_t(unsigned int, size, vi->data_avail); - memcpy(buf, vi->data + vi->data_idx, size); + unsigned int idx, avail; + + /* + * vi->data_avail was set from the device-reported used.len and + * vi->data_idx was advanced by previous copy_data() calls. A + * malicious or buggy virtio-rng backend can drive either past + * sizeof(vi->data). Clamp at point of use and harden the index + * with array_index_nospec() so the memcpy() below cannot be + * steered into adjacent slab memory, including under + * speculation. + */ + avail = min_t(unsigned int, vi->data_avail, sizeof(vi->data)); + if (vi->data_idx >= avail) { + vi->data_avail = 0; + request_entropy(vi); + return 0; + } + size = min_t(unsigned int, size, avail - vi->data_idx); + idx = array_index_nospec(vi->data_idx, sizeof(vi->data)); + memcpy(buf, vi->data + idx, size); vi->data_idx += size; vi->data_avail -= size; if (vi->data_avail == 0) -- 2.34.1

2 1

[PATCH OLK-5.10 0/2] CVE-2026-64560
by Jinjie Ruan 03 Aug '26

03 Aug '26

CVE-2026-64560. Peter Zijlstra (1): locking: Introduce __cleanup() based infrastructure Thomas Gleixner (1): posix-cpu-timers: Prevent UAF caused by non-leader exec() race drivers/dma/ioat/dma.c | 12 +- include/linux/cleanup.h | 171 +++++++++++++++++++++++++ include/linux/compiler-clang.h | 9 ++ include/linux/compiler_attributes.h | 6 + include/linux/device.h | 7 ++ include/linux/file.h | 6 + include/linux/irqflags.h | 7 ++ include/linux/mutex.h | 4 + include/linux/percpu.h | 4 + include/linux/preempt.h | 5 + include/linux/rcupdate.h | 3 + include/linux/rwsem.h | 9 ++ include/linux/sched/task.h | 2 + include/linux/slab.h | 4 +- include/linux/spinlock.h | 32 +++++ include/linux/srcu.h | 5 + kernel/exit.c | 8 +- kernel/signal.c | 10 +- kernel/time/posix-cpu-timers.c | 185 ++++++++++++++++++---------- scripts/checkpatch.pl | 2 +- 20 files changed, 417 insertions(+), 74 deletions(-) create mode 100644 include/linux/cleanup.h -- 2.34.1

2 3

[PATCH OLK-6.6 v3 0/5] bpf mainline
by Pu Lehui 03 Aug '26

03 Aug '26

David Windsor (1): bpf: Reject sleepable BPF_LSM_CGROUP programs at load time Jiri Olsa (1): bpf: Guard __get_user acesss with access_ok for uprobe_multi data Kaitao Cheng (1): bpf: Clear rb node linkage when freeing bpf_rb_root Xu Kuohai (2): bpf: Fix setting retval to -EPERM for cgroup hooks not returning errno bpf: Add validation for bpf_set_retval argument include/linux/bpf_lsm.h | 6 ++++ kernel/bpf/bpf_lsm.c | 20 ++++++++++++ kernel/bpf/cgroup.c | 47 ++++++++++++++++++++-------- kernel/bpf/helpers.c | 11 +++++-- kernel/bpf/verifier.c | 67 +++++++++++++++++++++++++++++++++++++--- kernel/trace/bpf_trace.c | 11 +++++++ 6 files changed, 143 insertions(+), 19 deletions(-) -- 2.34.1

2 6

[PATCH OLK-6.6] firmware_loader: fix device reference leak in firmware_upload_register()
by Zhang Yuwei 03 Aug '26

03 Aug '26

From: Guangshuo Li <lgs201920130244(a)gmail.com> stable inclusion from stable-v6.6.145 commit 46d403da376a8b7c1187193294953816e1a8d7fe category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16671 CVE: CVE-2026-64376 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 896df22ee57648b0c505bd76ddbc6b2341834696 upstream. firmware_upload_register() -> fw_create_instance() -> device_initialize() After fw_create_instance() succeeds, the lifetime of the embedded struct device is expected to be managed through the device core reference counting, since fw_create_instance() has already called device_initialize(). In firmware_upload_register(), if alloc_lookup_fw_priv() fails after fw_create_instance() succeeds, the code reaches free_fw_sysfs and frees fw_sysfs directly instead of releasing the device reference with put_device(). This may leave the reference count of the embedded struct device unbalanced, resulting in a refcount leak. The issue was identified by a static analysis tool I developed and confirmed by manual review. Fix this by using put_device(fw_dev) in the failure path and letting fw_dev_release() handle the final cleanup, instead of freeing the instance directly from the error path. Fixes: 97730bbb242c ("firmware_loader: Add firmware-upload support") Cc: stable(a)vger.kernel.org Signed-off-by: Guangshuo Li <lgs201920130244(a)gmail.com> Link: https://patch.msgid.link/20260505091231.607089-1-lgs201920130244@gmail.com Signed-off-by: Danilo Krummrich <dakr(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Hulk Robot <hulkrobot(a)huawei.com> Signed-off-by: Zhang Yuwei <zhangyuwei20(a)huawei.com> --- drivers/base/firmware_loader/sysfs_upload.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/base/firmware_loader/sysfs_upload.c b/drivers/base/firmware_loader/sysfs_upload.c index a0af8f5f13d8..54a1abae3948 100644 --- a/drivers/base/firmware_loader/sysfs_upload.c +++ b/drivers/base/firmware_loader/sysfs_upload.c @@ -340,7 +340,6 @@ firmware_upload_register(struct module *module, struct device *parent, goto free_fw_upload_priv; } fw_upload->priv = fw_sysfs; - fw_sysfs->fw_upload_priv = fw_upload_priv; fw_dev = &fw_sysfs->dev; ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, NULL, 0, 0, @@ -348,10 +347,12 @@ firmware_upload_register(struct module *module, struct device *parent, if (ret != 0) { if (ret > 0) ret = -EINVAL; - goto free_fw_sysfs; + put_device(fw_dev); + goto free_fw_upload_priv; } fw_priv->is_paged_buf = true; fw_sysfs->fw_priv = fw_priv; + fw_sysfs->fw_upload_priv = fw_upload_priv; ret = device_add(fw_dev); if (ret) { @@ -362,9 +363,6 @@ firmware_upload_register(struct module *module, struct device *parent, return fw_upload; -free_fw_sysfs: - kfree(fw_sysfs); - free_fw_upload_priv: kfree(fw_upload_priv); -- 2.22.0

2 1

[PATCH OLK-6.6] firmware_loader: fix device reference leak in firmware_upload_register()
by Zhang Yuwei 03 Aug '26

03 Aug '26

From: Guangshuo Li <lgs201920130244(a)gmail.com> stable inclusion from stable-v6.6.145 commit 46d403da376a8b7c1187193294953816e1a8d7fe category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16671 CVE: CVE-2026-64376 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 896df22ee57648b0c505bd76ddbc6b2341834696 upstream. firmware_upload_register() -> fw_create_instance() -> device_initialize() After fw_create_instance() succeeds, the lifetime of the embedded struct device is expected to be managed through the device core reference counting, since fw_create_instance() has already called device_initialize(). In firmware_upload_register(), if alloc_lookup_fw_priv() fails after fw_create_instance() succeeds, the code reaches free_fw_sysfs and frees fw_sysfs directly instead of releasing the device reference with put_device(). This may leave the reference count of the embedded struct device unbalanced, resulting in a refcount leak. The issue was identified by a static analysis tool I developed and confirmed by manual review. Fix this by using put_device(fw_dev) in the failure path and letting fw_dev_release() handle the final cleanup, instead of freeing the instance directly from the error path. Fixes: 97730bbb242c ("firmware_loader: Add firmware-upload support") Cc: stable(a)vger.kernel.org Signed-off-by: Guangshuo Li <lgs201920130244(a)gmail.com> Link: https://patch.msgid.link/20260505091231.607089-1-lgs201920130244@gmail.com Signed-off-by: Danilo Krummrich <dakr(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Hulk Robot <hulkrobot(a)huawei.com> --- drivers/base/firmware_loader/sysfs_upload.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/base/firmware_loader/sysfs_upload.c b/drivers/base/firmware_loader/sysfs_upload.c index a0af8f5f13d8..54a1abae3948 100644 --- a/drivers/base/firmware_loader/sysfs_upload.c +++ b/drivers/base/firmware_loader/sysfs_upload.c @@ -340,7 +340,6 @@ firmware_upload_register(struct module *module, struct device *parent, goto free_fw_upload_priv; } fw_upload->priv = fw_sysfs; - fw_sysfs->fw_upload_priv = fw_upload_priv; fw_dev = &fw_sysfs->dev; ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, NULL, 0, 0, @@ -348,10 +347,12 @@ firmware_upload_register(struct module *module, struct device *parent, if (ret != 0) { if (ret > 0) ret = -EINVAL; - goto free_fw_sysfs; + put_device(fw_dev); + goto free_fw_upload_priv; } fw_priv->is_paged_buf = true; fw_sysfs->fw_priv = fw_priv; + fw_sysfs->fw_upload_priv = fw_upload_priv; ret = device_add(fw_dev); if (ret) { @@ -362,9 +363,6 @@ firmware_upload_register(struct module *module, struct device *parent, return fw_upload; -free_fw_sysfs: - kfree(fw_sysfs); - free_fw_upload_priv: kfree(fw_upload_priv); -- 2.22.0

2 1

[PATCH OLK-6.6 v2] bpf: Support for hardening against JIT spraying
by Pu Lehui 02 Aug '26

02 Aug '26

From: Pawan Gupta <pawan.kumar.gupta(a)linux.intel.com> stable inclusion from stable-v6.6.145 commit 6e52c240c43a601b681e3a4e58fc5685114d4726 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9711 CVE: CVE-2026-64508 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 96cce16e26dd02a8678f1e87f88a4b5cdb63b995 upstream. The BPF JIT allocator packs many small programs into larger executable allocations and reuses space within those allocations as programs are loaded and freed. When fresh code is written into space that a previous program occupied, an indirect jump into the new program can reuse a branch prediction left behind by the old one. Flush the indirect branch predictors before reusing JIT memory so that indirect jumps into a newly written program don't reuse predictions from an old program that occupied the same space. Introduce bpf_arch_pred_flush_enabled static key and bpf_arch_pred_flush static call for flushing the branch predictors on JIT memory reuse. Architectures that need a flush, can update it to a predictor flush function. By default, its a NOP and does not emit any CALL. Allocations larger than a pack are not covered by this flush. That is safe because cBPF programs (the unprivileged attack surface) are bounded well below a pack size. Issue a warning if this assumption is ever violated while the flush is active. Signed-off-by: Pawan Gupta <pawan.kumar.gupta(a)linux.intel.com> Acked-by: Daniel Borkmann <daniel(a)iogearbox.net> Signed-off-by: Daniel Borkmann <daniel(a)iogearbox.net> Signed-off-by: Sasha Levin <sashal(a)kernel.org> Signed-off-by: Pu Lehui <pulehui(a)huawei.com> --- include/linux/filter.h | 10 ++++++++++ kernel/bpf/core.c | 19 +++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/linux/filter.h b/include/linux/filter.h index 2136040bbaea..cb693a4c54c4 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -22,6 +22,7 @@ #include <linux/vmalloc.h> #include <linux/sockptr.h> #include <crypto/sha1.h> +#include <linux/static_call.h> #include <linux/u64_stats_sync.h> #include <net/sch_generic.h> @@ -1039,6 +1040,15 @@ extern long bpf_jit_limit_max; typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size); +/* + * Flush the indirect branch predictors before reusing JIT memory, so that + * indirect jumps into a newly written program don't reuse predictions left + * behind by an old program that occupied the same space. + */ +void bpf_arch_pred_flush(void); +DECLARE_STATIC_CALL(bpf_arch_pred_flush, bpf_arch_pred_flush); +DECLARE_STATIC_KEY_FALSE(bpf_pred_flush_enabled); + void bpf_jit_fill_hole_with_zero(void *area, unsigned int size); struct bpf_binary_header * diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 7f9a5f46226a..f53f401ae72b 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -37,6 +37,7 @@ #include <linux/nospec.h> #include <linux/bpf_mem_alloc.h> #include <linux/memcontrol.h> +#include <linux/static_call.h> #include <asm/barrier.h> #include <asm/unaligned.h> @@ -884,6 +885,15 @@ void bpf_jit_fill_hole_with_zero(void *area, unsigned int size) memset(area, 0, size); } +DEFINE_STATIC_CALL_NULL(bpf_arch_pred_flush, bpf_arch_pred_flush); + +/* + * Enabled once bpf_arch_pred_flush points at a real flush routine. Lets the + * pack allocator test "is a predictor flush wired up at all" with a cheap + * static branch instead of repeatedly querying the static call target. + */ +DEFINE_STATIC_KEY_FALSE(bpf_pred_flush_enabled); + #define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE) static DEFINE_MUTEX(pack_mutex); @@ -943,6 +953,14 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) mutex_lock(&pack_mutex); if (size > BPF_PROG_PACK_SIZE) { + /* + * Allocations larger than a pack get their own pages, and + * predictors are not flushed for such allocation. This is only + * safe because cBPF programs (the unprivileged attack surface) + * are bounded well below a pack size. + */ + if (static_branch_unlikely(&bpf_pred_flush_enabled)) + pr_warn_once("BPF: Predictors not flushed for allocations greater than BPF_PROG_PACK_SIZE\n"); size = round_up(size, PAGE_SIZE); ptr = bpf_jit_alloc_exec(size); if (ptr) { @@ -973,6 +991,7 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) pos = 0; found_free_area: + static_call_cond(bpf_arch_pred_flush)(); bitmap_set(pack->bitmap, pos, nbits); ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); -- 2.34.1

2 1

[PATCH OLK-5.10] posix-cpu-timers: Prevent UAF caused by non-leader exec() race
by Jinjie Ruan 31 Jul '26

31 Jul '26

From: Thomas Gleixner <tglx(a)kernel.org> stable inclusion from stable-v5.10.262 commit 67aa823e3e8c229c6d374df79c804f6721cb83b6 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16862 CVE: CVE-2026-64560 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 920f893f735e92ba3a1cd9256899a186b161928d upstream. Wongi and Jungwoo decoded and reported a non-leader exec() related race which can result in an UAF: sys_timer_delete() exec() posix_cpu_timer_del() // Observes old leader p = pid_task(pid, pid_type); de_thread() switch_leader(); release_task(old_leader) __exit_signal(old_leader) sighand = lock(old_leader, sighand); posix_cpu_timers*_exit(); sighand = lock_task_sighand(p) unhash_task(old_leader); sh = lock(p, sighand) old_leader->sighand = NULL; unlock(sighand); (p->sighand == NULL) unlock(sh) return NULL; // Returns without action if(!sighand) return 0; free_posix_timer(); This is "harmless" unless the deleted timer was armed and enqueued in p->signal because on exec() a TGID targeted timer is inherited. As sys_timer_delete() freed the underlying posix timer object run_posix_cpu_timers() or any timerqueue related add/delete operations on other timers will access the freed object's timerqueue node, which results in an UAF. There is a similar problem vs. posix_cpu_timer_set(). For regular posix timers it just transiently returns -ESRCH to user space, but for the use case in do_cpu_nanosleep() it's the same UAF just that the k_itimer is allocated on the stack. Also posix_cpu_timer_rearm() fails to rearm the timer, which means it stops to expire. While debating solutions Frederic pointed out another problem: posix_cpu_timer_del(tmr) __exit_signal(p) posix_cpu_timers*_exit(p); unhash_task(p); p->sighand = NULL; sh = lock_task_sighand(p) sighand = p->sighand; if (!sighand) return NULL; lock(sighand); if (!sh) WARN_ON_ONCE(timer_queued(tmr)); On weakly ordered architectures it is not guaranteed that posix_cpu_timer_del() will observe the stores in posix_cpu_timers*_exit() when p->sighand is observed as NULL, which means the WARN() can be a false positive. Solve these issues by: 1) Changing the store in __exit_signal() to smp_store_release(). 2) Adding a smp_acquire__after_ctrl_dep() into the !sighand path of lock_task_sighand(). 3) Creating a helper function for looking up the task and locking sighand which does not return when sighand == NULL. Instead it retries the task lookup and only if that fails it gives up. 4) Using that helper in the three affected functions. observes all preceeding stores, i.e. the stores in posix_cpu_timers*_exit() and the ones in unhash_task(). gracefully. When the task lookup returns the old leader, but sighand == NULL then it retries. In the non-leader exec() case the subsequent task lookup will observe the new leader due to #1/#2. In normal exit() scenarios the subsequent lookup fails. When the task lookup fails, the function also checks whether the timer is still enqueued and issues a warning if that's the case. Unfortunately there is nothing which can be done about it, but as the task is already not longer visible the timer should not be accessed anymore. This check also requires memory ordering, which is not provided when the first lookup fails. To achieve that the check is preceeded by a smp_rmb() which pairs with the smp_wmb() in write_seqlock() in __exit_signal(). That ensures that the stores in posix_cpu_timers*_exit() are visible. The history of the non-leader exec() issue goes back to the early days of posix CPU timers, which stored a pointer to the group leader task in the timer. That obviously fails when a non-leader exec() switches the leader. commit e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") added a temporary workaround for that in 2010 which survived about 10 years. The fix for the workaround changed the task pointer to a pid pointer, but failed to see the subtle race described above. So the Fixes tag picks that commit, which seems to be halfways accurate. Thanks to Frederic Weissbecker, Oleg Nesterov and Peter Zijlstra for review, feedback and suggestions and to Wongi and Jungwoo for the excellent bug report and analysis! Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Reported-by: Wongi Lee <qw3rtyp0(a)gmail.com> Reported-by: Jungwoo Lee <jwlee2217(a)gmail.com> Signed-off-by: Thomas Gleixner <tglx(a)kernel.org> Reviewed-by: Oleg Nesterov <oleg(a)redhat.com> Cc: stable(a)vger.kernel.org Signed-off-by: Sasha Levin <sashal(a)kernel.org> Conflicts: kernel/time/posix-cpu-timers.c [ context conflicts. ] Signed-off-by: Jinjie Ruan <ruanjinjie(a)huawei.com> --- kernel/exit.c | 8 +- kernel/signal.c | 10 +- kernel/time/posix-cpu-timers.c | 185 +++++++++++++++++++++------------ 3 files changed, 137 insertions(+), 66 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 86b083f5fd60..3427e9514968 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -154,7 +154,13 @@ static void __exit_signal(struct task_struct *tsk) * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. */ flush_sigqueue(&tsk->pending); - tsk->sighand = NULL; + + /* + * Ensure that all preceeding state is visible. Pairs with + * the smp_acquire__after_ctrl_dep() in the sighand == NULL + * path of lock_task_sighand(). + */ + smp_store_release(&tsk->sighand, NULL); spin_unlock(&sighand->siglock); __cleanup_sighand(sighand); diff --git a/kernel/signal.c b/kernel/signal.c index 91d177e1023d..77e8c2eaab70 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1382,8 +1382,16 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, rcu_read_lock(); for (;;) { sighand = rcu_dereference(tsk->sighand); - if (unlikely(sighand == NULL)) + if (unlikely(sighand == NULL)) { + /* + * Pairs with the smp_store_release() in + * __exit_signal(). It ensures that all state + * modifications to the task preceeding the store are + * visible to the callers of lock_task_sighand(). + */ + smp_acquire__after_ctrl_dep(); break; + } /* * This sighand can be already freed and even reused, but diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 3e08c8991833..1a2f6ef4846e 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -405,6 +405,110 @@ static int posix_cpu_timer_create(struct k_itimer *new_timer) return 0; } +/* + * Lookup the task via timer->it.cpu.pid and attempt to lock the task's sighand. + * + * This can race with the reaping of the task: + * + * CPU0 CPU1 + * + * // Finds task + * p = pid_task(pid, pid_type); __exit_signal(p) + * lock(p, sighand); + * posix_cpu_timers*_exit(); + * sighand = lock_task_sighand(p); unhash_task(p); + * p->sighand = NULL; + * unlock(sighand); + * + * In this case sighand is NULL, which means the task and the associated timer + * queue cannot be longer accessed safely. + * + * __exit_signal() invokes posix_cpu_timers_exit() and if the thread group is + * dead it also invokes posix_cpu_timers_group_exit(). These functions delete + * all pending timers from the related timer queues. The POSIX timers (k_itimer) + * themself are still accessible, but not longer connected to the task. + * + * exec() works slightly differently. The task which exec()'s terminates all + * other threads in the thread group and runs __exit_signal() on them. As the + * thread group is not dead they only clean up the per task timers via + * posix_cpu_timers_exit(). + * + * As the TGID on exec() stays the same per process timers stay queued, if they + * are armed. This works without a problem when exec() is done by the thread + * group leader. If a non-leader thread exec()'s this can end up in the + * following scenario: + * + * CPU0 CPU1 + * // Returns old leader + * p = pid_task(pid, pid_type); de_thread() + * switch_leader() + * release_task(old leader) + * __exit_signal() + * old_leader->sighand = NULL; + * // Returns NULL + * sighand = lock_task_sighand(p) + * + * That's problematic for several functions: + * + * - posix_cpu_timer_del(): If the timer is still enqueued on the task the + * underlying k_itimer will be freed which results in a UAF in + * run_posix_cpu_timers() or on timerqueue related add/delete operations. + * If the timer is not enqueued, the failure is harmless + * + * - posix_cpu_timer_set(): Independent of the enqueued state that results in a + * transient failure which is user space visible (-ESRCH) for regular posix + * timers. But for the use case in do_cpu_nanosleep() it's the same UAF + * problem just that the timer is allocated on the stack. + * + * - posix_cpu_timer_rearm(): Timer is not enqueued at that point, but this + * silently ignores the rearm request, which is a functional problem as the + * timer wont expire anymore. + */ +static struct task_struct *timer_lock_sighand(struct k_itimer *timer, unsigned long *flags) +{ + enum pid_type type = clock_pid_type(timer->it_clock); + struct cpu_timer *ctmr = &timer->it.cpu; + + guard(rcu)(); + + for (;;) { + struct task_struct *t = pid_task(timer->it.cpu.pid, type); + + /* Fail if the task cannot be found. */ + if (!t) + break; + + /* Try to lock the task's sighand */ + if (lock_task_sighand(t, flags)) + return t; + + /* + * The next PID lookup might either fail or return the new + * leader. This is correct for both exit() and exec(). + */ + } + + /* + * If the timer is still enqueued, warn. There is nothing safe to do + * here as there might be two timers in there which are removed in + * parallel and that will cause more damage than good. This should never + * happen! + * + * Ensure that the stores to the timer and timerqueue are visible: + * + * __exit_signal() + * posix_cpu_timers*_exit() + * write_seqlock(seqlock) + * smp_wmb(); <------- + * __unhash_process() | !pid_task() + * ----> smp_rmb(); + * WARN_ON_ONCE(...) + */ + smp_rmb(); + WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node)); + return NULL; +} + /* * Clean up a CPU-clock timer that is about to be destroyed. * This is called from timer deletion with the timer already locked. @@ -414,28 +518,13 @@ static int posix_cpu_timer_create(struct k_itimer *new_timer) static int posix_cpu_timer_del(struct k_itimer *timer) { struct cpu_timer *ctmr = &timer->it.cpu; - struct sighand_struct *sighand; struct task_struct *p; unsigned long flags; int ret = 0; - rcu_read_lock(); - p = cpu_timer_task_rcu(timer); - if (!p) - goto out; + p = timer_lock_sighand(timer, &flags); - /* - * Protect against sighand release/switch in exit/exec and process/ - * thread timer list entry concurrent read/writes. - */ - sighand = lock_task_sighand(p, &flags); - if (unlikely(sighand == NULL)) { - /* - * This raced with the reaping of the task. The exit cleanup - * should have removed this timer from the timer queue. - */ - WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node)); - } else { + if (likely(p)) { if (timer->it.cpu.firing) ret = TIMER_RETRY; else @@ -444,8 +533,6 @@ static int posix_cpu_timer_del(struct k_itimer *timer) unlock_task_sighand(p, &flags); } -out: - rcu_read_unlock(); if (!ret) put_pid(ctmr->pid); @@ -575,37 +662,19 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock); u64 old_expires, new_expires, old_incr, val; struct cpu_timer *ctmr = &timer->it.cpu; - struct sighand_struct *sighand; struct task_struct *p; unsigned long flags; int ret = 0; - rcu_read_lock(); - p = cpu_timer_task_rcu(timer); - if (!p) { - /* - * If p has just been reaped, we can no - * longer get any information about it at all. - */ - rcu_read_unlock(); - return -ESRCH; - } - - new_expires = timespec64_to_ns(&new->it_value); - + p = timer_lock_sighand(timer, &flags); /* - * Protect against sighand release/switch in exit/exec and p->cpu_timers - * and p->signal->cpu_timers read/write in arm_timer() + * If p has just been reaped, we can no longer get any information about + * it at all. */ - sighand = lock_task_sighand(p, &flags); - /* - * If p has just been reaped, we can no - * longer get any information about it at all. - */ - if (unlikely(sighand == NULL)) { - rcu_read_unlock(); + if (!p) return -ESRCH; - } + + new_expires = timespec64_to_ns(&new->it_value); /* * Disarm any old timer after extracting its expiry time. @@ -655,6 +724,8 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, old->it_value.tv_sec = 0; } } + + old->it_interval = ns_to_timespec64(old_incr); } if (unlikely(ret)) { @@ -665,7 +736,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, * it as an overrun (thanks to bump_cpu_timer above). */ unlock_task_sighand(p, &flags); - goto out; + return ret; } if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) { @@ -682,7 +753,6 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, arm_timer(timer, p); } - unlock_task_sighand(p, &flags); /* * Install the new reload setting, and * set up the signal and overrun bookkeeping. @@ -699,6 +769,8 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, timer->it_overrun_last = 0; timer->it_overrun = -1; + unlock_task_sighand(p, &flags); + if (new_expires != 0 && !(val < new_expires)) { /* * The designated time already passed, so we notify @@ -708,13 +780,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, cpu_timer_fire(timer); } - ret = 0; - out: - rcu_read_unlock(); - if (old) - old->it_interval = ns_to_timespec64(old_incr); - - return ret; + return 0; } static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp) @@ -978,19 +1044,12 @@ static void posix_cpu_timer_rearm(struct k_itimer *timer) { clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock); struct task_struct *p; - struct sighand_struct *sighand; unsigned long flags; u64 now; - rcu_read_lock(); - p = cpu_timer_task_rcu(timer); - if (!p) - goto out; - - /* Protect timer list r/w in arm_timer() */ - sighand = lock_task_sighand(p, &flags); - if (unlikely(sighand == NULL)) - goto out; + p = timer_lock_sighand(timer, &flags); + if (unlikely(!p)) + return; /* * Fetch the current sample and update the timer's expiry time. @@ -1007,8 +1066,6 @@ static void posix_cpu_timer_rearm(struct k_itimer *timer) */ arm_timer(timer, p); unlock_task_sighand(p, &flags); -out: - rcu_read_unlock(); } /** -- 2.34.1

2 1

[PATCH OLK-6.6 0/5] mainline bpf
by Pu Lehui 31 Jul '26

31 Jul '26

David Windsor (1): bpf: Reject sleepable BPF_LSM_CGROUP programs at load time Jiri Olsa (1): bpf: Guard __get_user acesss with access_ok for uprobe_multi data Kaitao Cheng (1): bpf: Clear rb node linkage when freeing bpf_rb_root Xu Kuohai (2): bpf: Fix setting retval to -EPERM for cgroup hooks not returning errno bpf: Add validation for bpf_set_retval argument include/linux/bpf_lsm.h | 6 ++++ kernel/bpf/bpf_lsm.c | 20 ++++++++++++ kernel/bpf/cgroup.c | 47 ++++++++++++++++++++-------- kernel/bpf/helpers.c | 11 +++++-- kernel/bpf/verifier.c | 67 +++++++++++++++++++++++++++++++++++++--- kernel/trace/bpf_trace.c | 11 +++++++ 6 files changed, 143 insertions(+), 19 deletions(-) -- 2.34.1

2 6

[PATCH openEuler-1.0-LTS] PCI: Remove old_size limit from bridge window sizing
by Hongtao Zhang 31 Jul '26

31 Jul '26

From: Ilpo Järvinen <ilpo.jarvinen(a)linux.intel.com> mainline inclusion from mainline-v7.0-rc1 commit f909e3ee3ed1a44202f09ac7e637a0f9ec372225 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9709 Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit… -------------------------------- calculate_memsize() applies lower bound to the resource size before aligning the resource size making it impossible to shrink bridge window resources. I've not found any justification for this lower bound and nothing indicated it was to work around some HW issue. Prior to the commit 3baeae36039a ("PCI: Use pci_release_resource() instead of release_resource()"), releasing a bridge window during BAR resize resulted in clearing start and end address of the resource. Clearing addresses destroys the resource size as a side-effect, therefore nullifying the effect of the old size lower bound. After the commit 3baeae36039a ("PCI: Use pci_release_resource() instead of release_resource()"), BAR resize uses the aligned old size, which results in exceeding what fits into the parent window in some cases: xe 0030:03:00.0: [drm] Attempting to resize bar from 256MiB -> 16384MiB xe 0030:03:00.0: BAR 0 [mem 0x620c000000000-0x620c000ffffff 64bit]: releasing xe 0030:03:00.0: BAR 2 [mem 0x6200000000000-0x620000fffffff 64bit pref]: releasing pci 0030:02:01.0: bridge window [mem 0x6200000000000-0x620001fffffff 64bit pref]: releasing pci 0030:01:00.0: bridge window [mem 0x6200000000000-0x6203fbff0ffff 64bit pref]: releasing pci 0030:00:00.0: bridge window [mem 0x6200000000000-0x6203fbff0ffff 64bit pref]: was not released (still contains assigned resources) pci 0030:00:00.0: Assigned bridge window [mem 0x6200000000000-0x6203fbff0ffff 64bit pref] to [bus 01-04] free space at [mem 0x6200400000000-0x62007ffffffff 64bit pref] pci 0030:00:00.0: Assigned bridge window [mem 0x6200000000000-0x6203fbff0ffff 64bit pref] to [bus 01-04] cannot fit 0x4000000000 required for 0030:01:00.0 bridging to [bus 02-04] The old size of 0x6200000000000-0x6203fbff0ffff resource was used as the lower bound which results in 0x4000000000 size request due to alignment. That exceeds what can fit into the parent window. Since the lower bound never even was enforced fully because the resource addresses were cleared when the bridge window is released, remove the old_size lower bound entirely and trust the calculated bridge window size is enough. This same problem may occur on io window side but seems less likely to cause issues due to general difference in alignment. Removing the lower bound may have other unforeseen consequences in case of io window so it's better to leave it as -next material if no problem is reported related to io window sizing (BAR resize shouldn't touch io windows anyway). Fixes: 3baeae36039a ("PCI: Use pci_release_resource() instead of release_resource()") Reported-by: Simon Richter <Simon.Richter(a)hogyros.de> Link: https://lore.kernel.org/r/f9a8c975-f5d3-4dd2-988e-4371a1433a60@hogyros.de/ Signed-off-by: Ilpo Järvinen <ilpo.jarvinen(a)linux.intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas(a)google.com> Link: https://patch.msgid.link/20251219174036.16738-6-ilpo.jarvinen@linux.intel.c… Conflicts: drivers/pci/setup-bus.c [conflicts due to not mergered prerequisites] Signed-off-by: Zhang Hongtao <zhanghongtao35(a)huawei.com> --- drivers/pci/setup-bus.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 39d19302f3cbe..fe6f68d9e465b 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -794,15 +794,10 @@ static resource_size_t calculate_iosize(resource_size_t size, static resource_size_t calculate_memsize(resource_size_t size, resource_size_t min_size, resource_size_t size1, - resource_size_t old_size, resource_size_t align) { if (size < min_size) size = min_size; - if (old_size == 1) - old_size = 0; - if (size < old_size) - size = old_size; size = ALIGN(size + size1, align); return size; } @@ -1041,13 +1036,12 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, min_align = calculate_mem_align(aligns, max_order); min_align = max(min_align, window_alignment(bus, b_res->flags)); - size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align); + size0 = calculate_memsize(size, min_size, 0, min_align); add_align = max(min_align, add_align); if (children_add_size > add_size) add_size = children_add_size; size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 : - calculate_memsize(size, min_size, add_size, - resource_size(b_res), add_align); + calculate_memsize(size, min_size, add_size, add_align); if (!size0 && !size1) { if (b_res->start || b_res->end) pci_info(bus->self, "disabling bridge window %pR to %pR (unused)\n", -- 2.43.0

2 1