In the Linux kernel, the following vulnerability has been resolved:
timers: Fix NULL function pointer race in timer_shutdown_sync()
There is a race condition between timer_shutdown_sync() and timer
expiration that can lead to hitting a WARN_ON in expire_timers().
The issue occurs when timer_shutdown_sync() clears the timer function
to NULL while the timer is still running on another CPU. The race
scenario looks like this:
CPU0 CPU1
<SOFTIRQ>
lock_timer_base()
expire_timers()
base->running_timer = timer;
unlock_timer_base()
[call_timer_fn enter]
mod_timer()
...
timer_shutdown_sync()
lock_timer_base()
// For now, will not detach the timer but only clear its function to NULL
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
if (shutdown)
timer->function = NULL;
unlock_timer_base()
[call_timer_fn exit]
lock_timer_base()
base->running_timer = NULL;
unlock_timer_base()
...
// Now timer is pending while its function set to NULL.
// next timer trigger
<SOFTIRQ>
expire_timers()
WARN_ON_ONCE(!fn) // hit
...
lock_timer_base()
// Now timer will detach
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
if (shutdown)
timer->function = NULL;
unlock_timer_base()
The problem is that timer_shutdown_sync() clears the timer function
regardless of whether the timer is currently running. This can leave a
pending timer with a NULL function pointer, which triggers the
WARN_ON_ONCE(!fn) check in expire_timers().
Fix this by only clearing the timer function when actually detaching the
timer. If the timer is running, leave the function pointer intact, which is
safe because the timer will be properly detached when it finishes running.
References
Configurations
Configuration 1 (hide)
|
History
26 Feb 2026, 15:52
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/176725f4848376530a0f0da9023f956afcc33585 - Patch | |
| References | () https://git.kernel.org/stable/c/1a975716cc8977f461e45e28e3e5977d46ad7a6a - Patch | |
| References | () https://git.kernel.org/stable/c/20739af07383e6eb1ec59dcd70b72ebfa9ac362c - Patch | |
| References | () https://git.kernel.org/stable/c/6665fbd7730b26d770c232b20d1b907e6a67a914 - Patch | |
| References | () https://git.kernel.org/stable/c/a01efa7a780c42ac5170a949bd95c9786ffcc60a - Patch | |
| References | () https://git.kernel.org/stable/c/ba43ac025c4318241f8edf94f31d2eebab86991b - Patch | |
| First Time |
Linux
Linux linux Kernel |
|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 4.7 |
| CWE | CWE-362 | |
| CPE | cpe:2.3:o:linux:linux_kernel:6.1.158:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.18:rc4:*:*:*:*:*:* |
12 Feb 2026, 09:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
16 Dec 2025, 14:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-12-16 14:15
Updated : 2026-02-26 15:52
NVD link : CVE-2025-68214
Mitre link : CVE-2025-68214
CVE.ORG link : CVE-2025-68214
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-362
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')