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cgroup/cpuset: Prevent NULL pointer access in free_tmpmasks()

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Commit 5806b3d051 ("cpuset: decouple tmpmasks and cpumasks freeing in
cgroup") separates out the freeing of tmpmasks into a new free_tmpmask()
helper but removes the NULL pointer check in the process. Unfortunately a
NULL pointer can be passed to free_tmpmasks() in cpuset_handle_hotplug()
if cpuset v1 is active. This can cause segmentation fault and crash
the kernel.

Fix that by adding the NULL pointer check to free_tmpmasks().

Fixes: 5806b3d051 ("cpuset: decouple tmpmasks and cpumasks freeing in cgroup")
Reported-by: Ashay Jaiswal <quic_ashayj@quicinc.com>
Closes: https://lore.kernel.org/lkml/20250902-cpuset-free-on-condition-v1-1-f46ffab53eac@quicinc.com/
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long
2025-09-02 14:15:37 -04:00
committed by Tejun Heo
parent 3b0dec689a
commit e117ff1129
1 changed files with 3 additions and 0 deletions
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kernel/cgroup/cpuset.c
+3
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@@ -484,6 +484,9 @@ static inline int alloc_tmpmasks(struct tmpmasks *tmp)
*/
static inline void free_tmpmasks(struct tmpmasks *tmp)
{
if (!tmp)
return;
free_cpumask_var(tmp->new_cpus);
free_cpumask_var(tmp->addmask);
free_cpumask_var(tmp->delmask);