Commit 5498bf28 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: annotate offset timeout races 



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: default avatar <syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com>
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4de3685e185832a92a572df2be2c735d2e21a83d.1684506056.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3af0356c

io_uring/timeout.c

+1 −1
Original line number Diff line number Diff line
@@ -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.