Description (CNA)
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. ]
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected bd27568117664b8b3e259721393df420ed51f57b before f0c3971405cef6892844016aa710121a02da3a23; affected bd27568117664b8b3e259721393df420ed51f57b before 7d582eb6e4e100959ba07083d7563453c8c2a343; affected bd27568117664b8b3e259721393df420ed51f57b before 3e812a70732d84b7873cea61a7f6349b9a9dcbf5; affected bd27568117664b8b3e259721393df420ed51f57b before 2016066c66192a99d9e0ebf433789c490a6785a2 |
| Linux / Linux | affected 6.2; unaffected 0 before 6.2; unaffected 6.6.81 through 6.6.*; unaffected 6.12.18 through 6.12.*; unaffected 6.13.6 through 6.13.*; unaffected 6.14 through * |
CWE
No CWE identifiers supplied.