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io_uring: annotate offset timeout races

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It's racy to read ->cached_cq_tail without taking proper measures
(usually grabbing ->completion_lock) as timeout requests with CQE
offsets do, however they have never had a good semantics for from
when they start counting. Annotate racy reads with data_race().

Reported-by: syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4de3685e185832a92a572df2be2c735d2e21a83d.1684506056.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-05-19 15:21:16 +01:00 committed by Jens Axboe
parent 3af0356c16
commit 5498bf28d8
1 changed files with 1 additions and 1 deletions
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2
io_uring/timeout.c
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@ -594,7 +594,7 @@ int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
goto add;
}
tail = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
timeout->target_seq = tail + off;
/* Update the last seq here in case io_flush_timeouts() hasn't.