diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2022-05-20 20:38:06 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-25 09:17:55 +0200 |
| commit | 3ee8e109c3c316073a3e0f83ec0769c7ee8a7375 (patch) | |
| tree | a9d7952b8417c071d105848b7034522b36fa8bb1 /kernel/acct.c | |
| parent | 18fb7d533c79909675749f1795dc312246143c6d (diff) | |
perf: Fix sys_perf_event_open() race against self
commit 3ac6487e584a1eb54071dbe1212e05b884136704 upstream.
Norbert reported that it's possible to race sys_perf_event_open() such
that the looser ends up in another context from the group leader,
triggering many WARNs.
The move_group case checks for races against itself, but the
!move_group case doesn't, seemingly relying on the previous
group_leader->ctx == ctx check. However, that check is racy due to not
holding any locks at that time.
Therefore, re-check the result after acquiring locks and bailing
if they no longer match.
Additionally, clarify the not_move_group case from the
move_group-vs-move_group race.
Fixes: f63a8daa5812 ("perf: Fix event->ctx locking")
Reported-by: Norbert Slusarek <nslusarek@gmx.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/acct.c')
0 files changed, 0 insertions, 0 deletions