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perf: Fix use-after-free in error path

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The syscall error path has a use-after-free; put_pmu_ctx() will
reference ctx, therefore we must ensure ctx is destroyed after pmu_ctx
is.

Fixes: bd27568117 ("perf: Rewrite core context handling")
Reported-by: syzbot+b8e8c01c8ade4fe6e48f@syzkaller.appspotmail.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lkml.kernel.org/r/Y6B3xEgkbmFUCeni@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2022-12-19 15:40:04 +01:00
parent 08245672cd
commit a551844e34
1 changed files with 3 additions and 1 deletions
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4
kernel/events/core.c
View file

@ -12671,7 +12671,8 @@ SYSCALL_DEFINE5(perf_event_open,
return event_fd;
err_context:
/* event->pmu_ctx freed by free_event() */
put_pmu_ctx(event->pmu_ctx);
event->pmu_ctx = NULL; /* _free_event() */
err_locked:
mutex_unlock(&ctx->mutex);
perf_unpin_context(ctx);
@ -12784,6 +12785,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
err_pmu_ctx:
put_pmu_ctx(pmu_ctx);
event->pmu_ctx = NULL; /* _free_event() */
err_unlock:
mutex_unlock(&ctx->mutex);
perf_unpin_context(ctx);