diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2014-05-29 19:00:24 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-06-05 12:29:52 +0200 |
| commit | ebf905fc7a6e7c99c53b5afc888d8f950da90aff (patch) | |
| tree | 9b0c9289f1ac0f30fe14f9bb5a6a646023134f66 | |
| parent | 10b0256496fd6c162478547f7c6df1e052e87644 (diff) | |
perf: Fix use after free in perf_remove_from_context()
While that mutex should guard the elements, it doesn't guard against the
use-after-free that's from list_for_each_entry_rcu().
__perf_event_exit_task() can actually free the event.
And because list addition/deletion is guarded by both ctx->mutex and
ctx->lock, holding ctx->mutex is sufficient for reading the list, so we
don't actually need the rcu list iteration.
Fixes: 3a497f48637e ("perf: Simplify perf_event_exit_task_context()")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>
Cc: acme@ghostprotocols.net
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140529170024.GA2315@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/events/core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index ed50b094321..a62d142ad49 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7431,7 +7431,7 @@ __perf_event_exit_task(struct perf_event *child_event, static void perf_event_exit_task_context(struct task_struct *child, int ctxn) { - struct perf_event *child_event; + struct perf_event *child_event, *next; struct perf_event_context *child_ctx; unsigned long flags; @@ -7485,7 +7485,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn) */ mutex_lock(&child_ctx->mutex); - list_for_each_entry_rcu(child_event, &child_ctx->event_list, event_entry) + list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry) __perf_event_exit_task(child_event, child_ctx, child); mutex_unlock(&child_ctx->mutex); |