From: Hyunwoo Kim imv4bel@gmail.com
mainline inclusion from mainline master commit cacdb14b1c8d3804a3a7d31773bc7569837b71a4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5U1PE CVE: CVE-2022-41850
--------------------------------
roccat_report_event() is responsible for registering roccat-related reports in struct roccat_device.
int roccat_report_event(int minor, u8 const *data) { struct roccat_device *device; struct roccat_reader *reader; struct roccat_report *report; uint8_t *new_value;
device = devices[minor];
new_value = kmemdup(data, device->report_size, GFP_ATOMIC); if (!new_value) return -ENOMEM;
report = &device->cbuf[device->cbuf_end];
/* passing NULL is safe */ kfree(report->value); ...
The registered report is stored in the struct roccat_device member "struct roccat_report cbuf[ROCCAT_CBUF_SIZE];". If more reports are received than the "ROCCAT_CBUF_SIZE" value, kfree() the saved report from cbuf[0] and allocates a new reprot. Since there is no lock when this kfree() is performed, kfree() can be performed even while reading the saved report.
static ssize_t roccat_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct roccat_reader *reader = file->private_data; struct roccat_device *device = reader->device; struct roccat_report *report; ssize_t retval = 0, len; DECLARE_WAITQUEUE(wait, current);
mutex_lock(&device->cbuf_lock);
...
report = &device->cbuf[reader->cbuf_start]; /* * If report is larger than requested amount of data, rest of report * is lost! */ len = device->report_size > count ? count : device->report_size;
if (copy_to_user(buffer, report->value, len)) { retval = -EFAULT; goto exit_unlock; } ...
The roccat_read() function receives the device->cbuf report and delivers it to the user through copy_to_user(). If the N+ROCCAT_CBUF_SIZE th report is received while copying of the Nth report->value is in progress, the pointer that copy_to_user() is working on is kfree()ed and UAF read may occur. (race condition)
Since the device node of this driver does not set separate permissions, this is not a security vulnerability, but because it is used for requesting screen display of profile or dpi settings, a user using the roccat device can apply udev to this device node or There is a possibility to use it by giving.
Signed-off-by: Hyunwoo Kim imv4bel@gmail.com Signed-off-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Cai Xinchen caixinchen1@huawei.com Reviewed-by: Ruiqi Gong gongruiqi1@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- drivers/hid/hid-roccat.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c index 5be8de70c651..c9cec00b4e6e 100644 --- a/drivers/hid/hid-roccat.c +++ b/drivers/hid/hid-roccat.c @@ -260,6 +260,8 @@ int roccat_report_event(int minor, u8 const *data) if (!new_value) return -ENOMEM;
+ mutex_lock(&device->cbuf_lock); + report = &device->cbuf[device->cbuf_end];
/* passing NULL is safe */ @@ -279,6 +281,8 @@ int roccat_report_event(int minor, u8 const *data) reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE; }
+ mutex_unlock(&device->cbuf_lock); + wake_up_interruptible(&device->wait); return 0; }
From: Jann Horn jannh@google.com
stable inclusion from stable-v4.19.257 commit 6dbfc25d68d922736381988d64156a649ccf7bf1 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5USOP CVE: CVE-2022-42703
--------------------------------
commit 2555283eb40df89945557273121e9393ef9b542b upstream.
anon_vma->degree tracks the combined number of child anon_vmas and VMAs that use the anon_vma as their ->anon_vma.
anon_vma_clone() then assumes that for any anon_vma attached to src->anon_vma_chain other than src->anon_vma, it is impossible for it to be a leaf node of the VMA tree, meaning that for such VMAs ->degree is elevated by 1 because of a child anon_vma, meaning that if ->degree equals 1 there are no VMAs that use the anon_vma as their ->anon_vma.
This assumption is wrong because the ->degree optimization leads to leaf nodes being abandoned on anon_vma_clone() - an existing anon_vma is reused and no new parent-child relationship is created. So it is possible to reuse an anon_vma for one VMA while it is still tied to another VMA.
This is an issue because is_mergeable_anon_vma() and its callers assume that if two VMAs have the same ->anon_vma, the list of anon_vmas attached to the VMAs is guaranteed to be the same. When this assumption is violated, vma_merge() can merge pages into a VMA that is not attached to the corresponding anon_vma, leading to dangling page->mapping pointers that will be dereferenced during rmap walks.
Fix it by separately tracking the number of child anon_vmas and the number of VMAs using the anon_vma as their ->anon_vma.
Fixes: 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy") Cc: stable@kernel.org Acked-by: Michal Hocko mhocko@suse.com Acked-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Jann Horn jannh@google.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ma Wupeng mawupeng1@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- include/linux/rmap.h | 7 +++++-- mm/rmap.c | 29 ++++++++++++++++------------- 2 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 91ccae946716..c80bd129e939 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -39,12 +39,15 @@ struct anon_vma { atomic_t refcount;
/* - * Count of child anon_vmas and VMAs which points to this anon_vma. + * Count of child anon_vmas. Equals to the count of all anon_vmas that + * have ->parent pointing to this one, including itself. * * This counter is used for making decision about reusing anon_vma * instead of forking new one. See comments in function anon_vma_clone. */ - unsigned degree; + unsigned long num_children; + /* Count of VMAs whose ->anon_vma pointer points to this object. */ + unsigned long num_active_vmas;
struct anon_vma *parent; /* Parent of this anon_vma */
diff --git a/mm/rmap.c b/mm/rmap.c index 2db733c42799..c336dacfac52 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -82,7 +82,8 @@ static inline struct anon_vma *anon_vma_alloc(void) anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); if (anon_vma) { atomic_set(&anon_vma->refcount, 1); - anon_vma->degree = 1; /* Reference for first vma */ + anon_vma->num_children = 0; + anon_vma->num_active_vmas = 0; anon_vma->parent = anon_vma; /* * Initialise the anon_vma root to point to itself. If called @@ -190,6 +191,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma) anon_vma = anon_vma_alloc(); if (unlikely(!anon_vma)) goto out_enomem_free_avc; + anon_vma->num_children++; /* self-parent link for new root */ allocated = anon_vma; }
@@ -199,8 +201,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma) if (likely(!vma->anon_vma)) { vma->anon_vma = anon_vma; anon_vma_chain_link(vma, avc, anon_vma); - /* vma reference or self-parent link for new root */ - anon_vma->degree++; + anon_vma->num_active_vmas++; allocated = NULL; avc = NULL; } @@ -285,19 +286,19 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) anon_vma_chain_link(dst, avc, anon_vma);
/* - * Reuse existing anon_vma if its degree lower than two, - * that means it has no vma and only one anon_vma child. + * Reuse existing anon_vma if it has no vma and only one + * anon_vma child. * - * Do not chose parent anon_vma, otherwise first child - * will always reuse it. Root anon_vma is never reused: + * Root anon_vma is never reused: * it has self-parent reference and at least one child. */ if (!dst->anon_vma && src->anon_vma && - anon_vma != src->anon_vma && anon_vma->degree < 2) + anon_vma->num_children < 2 && + anon_vma->num_active_vmas == 0) dst->anon_vma = anon_vma; } if (dst->anon_vma) - dst->anon_vma->degree++; + dst->anon_vma->num_active_vmas++; unlock_anon_vma_root(root); return 0;
@@ -347,6 +348,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) anon_vma = anon_vma_alloc(); if (!anon_vma) goto out_error; + anon_vma->num_active_vmas++; avc = anon_vma_chain_alloc(GFP_KERNEL); if (!avc) goto out_error_free_anon_vma; @@ -367,7 +369,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) vma->anon_vma = anon_vma; anon_vma_lock_write(anon_vma); anon_vma_chain_link(vma, avc, anon_vma); - anon_vma->parent->degree++; + anon_vma->parent->num_children++; anon_vma_unlock_write(anon_vma);
return 0; @@ -399,7 +401,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma) * to free them outside the lock. */ if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) { - anon_vma->parent->degree--; + anon_vma->parent->num_children--; continue; }
@@ -407,7 +409,7 @@ void unlink_anon_vmas(struct vm_area_struct *vma) anon_vma_chain_free(avc); } if (vma->anon_vma) { - vma->anon_vma->degree--; + vma->anon_vma->num_active_vmas--;
/* * vma would still be needed after unlink, and anon_vma will be prepared @@ -425,7 +427,8 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { struct anon_vma *anon_vma = avc->anon_vma;
- VM_WARN_ON(anon_vma->degree); + VM_WARN_ON(anon_vma->num_children); + VM_WARN_ON(anon_vma->num_active_vmas); put_anon_vma(anon_vma);
list_del(&avc->same_vma);
From: Ma Wupeng mawupeng1@huawei.com
hulk inclusion category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5USOP CVE: CVE-2022-42703
--------------------------------
In order to fix CVE-2022-42703, degree in struct anon_vma is splited into two variables(num_children, num_active_vmas) and this will lead to broken kabi.
Since struct anon_vma is only used by mm module and referenced by other struct as pointers. So we can ignore this kabi change warning.
For variable degree in struct anon_vma, previous patch has already delete this but this will lead to kabi change. Add it back at the same position. For variables(num_children, num_active_vmas), put them between macro __GENKSYMS__.
Signed-off-by: Ma Wupeng mawupeng1@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- include/linux/rmap.h | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index c80bd129e939..5568caa9958f 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -38,16 +38,12 @@ struct anon_vma { */ atomic_t refcount;
- /* - * Count of child anon_vmas. Equals to the count of all anon_vmas that - * have ->parent pointing to this one, including itself. - * - * This counter is used for making decision about reusing anon_vma - * instead of forking new one. See comments in function anon_vma_clone. - */ - unsigned long num_children; - /* Count of VMAs whose ->anon_vma pointer points to this object. */ - unsigned long num_active_vmas; +#ifndef __GENKSYMS__ + unsigned __unused_degree; +#else + /* Add degree back for KABI compatibility */ + unsigned degree; +#endif
struct anon_vma *parent; /* Parent of this anon_vma */
@@ -62,6 +58,18 @@ struct anon_vma {
/* Interval tree of private "related" vmas */ struct rb_root_cached rb_root; +#ifndef __GENKSYMS__ + /* + * Count of child anon_vmas. Equals to the count of all anon_vmas that + * have ->parent pointing to this one, including itself. + * + * This counter is used for making decision about reusing anon_vma + * instead of forking new one. See comments in function anon_vma_clone. + */ + unsigned long num_children; + /* Count of VMAs whose ->anon_vma pointer points to this object. */ + unsigned long num_active_vmas; +#endif };
/*
-
Yongqiang Liu