ΠΠΏΠΈΡΠ°Π½ΠΈΠ΅
In the Linux kernel, the following vulnerability has been resolved:
drm/drm_file: Fix pid refcounting race
maarten.lankhorst@linux.intel.com, Maxime Ripard
mripard@kernel.org, Thomas Zimmermann tzimmermann@suse.de
filp->pid is supposed to be a refcounted pointer; however, before this
patch, drm_file_update_pid() only increments the refcount of a struct
pid after storing a pointer to it in filp->pid and dropping the
dev->filelist_mutex, making the following race possible:
process A process B
========= =========
begin drm_file_update_pid
mutex_lock(&dev->filelist_mutex)
rcu_replace_pointer(filp->pid, , 1)
mutex_unlock(&dev->filelist_mutex)
begin drm_file_update_pid
mutex_lock(&dev->filelist_mutex)
rcu_replace_pointer(filp->pid, , 1)
mutex_unlock(&dev->filelist_mutex)
get_pid()
synchronize_rcu()
put_pid() *** pid B reaches refcount 0 and is freed here ***
get_pid() *** UAF ***
synchronize_rcu()
put_pid()
As far as I know, this race can only occur with CONFIG_PREEMPT_RCU=y
because it requires RCU to detect a quiescent state in code that is not
explicitly calling into the scheduler.
This race leads to use-after-free of a "struct pid".
It is probably somewhat hard to hit because process A has to pass
through a synchronize_rcu() operation while process B is between
mutex_unlock() and get_pid().
Fix it by ensuring that by the time a pointer to the current task's pid
is stored in the file, an extra reference to the pid has been taken.
This fix also removes the condition for synchronize_rcu(); I think
that optimization is unnecessary complexity, since in that case we
would usually have bailed out on the lockless check above.
A race condition was found in the Linux kernel. The rm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid, dropping the dev->filelist_mutex, resulting in a use-after-free vulnerability.
ΠΠ΅ΡΡ ΠΏΠΎ ΡΠΌΡΠ³ΡΠ΅Π½ΠΈΡ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΠ²ΠΈΠΉ
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
ΠΠ°ΡΡΠΎΠ½ΡΡΡΠ΅ ΠΏΠ°ΠΊΠ΅ΡΡ
| ΠΠ»Π°ΡΡΠΎΡΠΌΠ° | ΠΠ°ΠΊΠ΅Ρ | Π‘ΠΎΡΡΠΎΡΠ½ΠΈΠ΅ | Π Π΅ΠΊΠΎΠΌΠ΅Π½Π΄Π°ΡΠΈΡ | Π Π΅Π»ΠΈΠ· |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Out of support scope | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2024:9315 | 12.11.2024 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2024:9315 | 12.11.2024 |
ΠΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡ ΠΏΠΎ
ΠΠΎΠΏΠΎΠ»Π½ΠΈΡΠ΅Π»ΡΠ½Π°Ρ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΡ
Π‘ΡΠ°ΡΡΡ:
EPSS
5.5 Medium
CVSS3
Π‘Π²ΡΠ·Π°Π½Π½ΡΠ΅ ΡΡΠ·Π²ΠΈΠΌΠΎΡΡΠΈ
In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de> filp->pid is supposed to be a refcounted pointer; however, before this patch, drm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelist_mutex, making the following race possible: process A process B ========= ========= begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid B>, 1) mutex_unlock(&dev->filelist_mutex) begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid A>, 1) mutex_unlock(&dev->filelist_mutex) get_pid(<pid A>) synchronize_rcu() put_pid(<pid B>) *** pid B reaches refcount 0 and is freed here *** get_pid(<pid B>) *** UAF *** synchronize_rcu() put_pid(<pid A>) As...
In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de> filp->pid is supposed to be a refcounted pointer; however, before this patch, drm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelist_mutex, making the following race possible: process A process B ========= ========= begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid B>, 1) mutex_unlock(&dev->filelist_mutex) begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid A>, 1) mutex_unlock(&dev->filelist_mutex) get_pid(<pid A>) synchronize_rcu() put_pid(<pid B>) *** pid B reaches refc
In the Linux kernel, the following vulnerability has been resolved: d ...
In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race filp->pid is supposed to be a refcounted pointer; however, before this patch, drm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelist_mutex, making the following race possible: process A process B ========= ========= begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid B>, 1) mutex_unlock(&dev->filelist_mutex) begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid A>, 1) mutex_unlock(&dev->filelist_mutex) get_pid(<pid A>) synchronize_rcu() put_pid(<pid B>) *** pid B reaches refcount 0 and is freed here *** get_pid(<pid B>) *** UAF *** sy...
EPSS
5.5 Medium
CVSS3