In the Linux kernel, the following vulnerability has been resolved:
perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list
Syskaller triggers a warning due to prev_epc->pmu != next_epc->pmu in
perf_event_swap_task_ctx_data(). vmcore shows that two lists have the same
perf_event_pmu_context, but not in the same order.
The problem is that the order of pmu_ctx_list for the parent is impacted by
the time when an event/PMU is added. While the order for a child is
impacted by the event order in the pinned_groups and flexible_groups. So
the order of pmu_ctx_list in the parent and child may be different.
To fix this problem, insert the perf_event_pmu_context to its proper place
after iteration of the pmu_ctx_list.
The follow testcase can trigger above warning:
# perf record -e cycles --call-graph lbr -- taskset -c 3 ./a.out &
# perf stat -e cpu-clock,cs -p xxx // xxx is the pid of a.out
test.c
void main() {
int count = 0;
pid_t pid;
printf("%d running\n", getpid());
sleep(30);
printf("running\n");
pid = fork();
if (pid == -1) {
printf("fork error\n");
return;
}
if (pid == 0) {
while (1) {
count++;
}
} else {
while (1) {
count++;
}
}
}
The testcase first opens an LBR event, so it will allocate task_ctx_data,
and then open tracepoint and software events, so the parent context will
have 3 different perf_event_pmu_contexts. On inheritance, child ctx will
insert the perf_event_pmu_context in another order and the warning will
trigger.
[ mingo: Tidied up the changelog. ]
References
Configurations
Configuration 1 (hide)
|
History
31 Oct 2025, 18:50
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/2016066c66192a99d9e0ebf433789c490a6785a2 - Patch | |
| References | () https://git.kernel.org/stable/c/3e812a70732d84b7873cea61a7f6349b9a9dcbf5 - Patch | |
| References | () https://git.kernel.org/stable/c/7d582eb6e4e100959ba07083d7563453c8c2a343 - Patch | |
| References | () https://git.kernel.org/stable/c/f0c3971405cef6892844016aa710121a02da3a23 - Patch | |
| First Time |
Linux linux Kernel
Linux |
|
| CWE | CWE-362 | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 4.7 |
| CPE | cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* |
Information
Published : 2025-04-01 16:15
Updated : 2025-10-31 18:50
NVD link : CVE-2025-21895
Mitre link : CVE-2025-21895
CVE.ORG link : CVE-2025-21895
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-362
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')