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io_uring: fix io_prep_async_link locking

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io_prep_async_link() may be called after arming a linked timeout,
automatically making it unsafe to traverse the linked list. Guard
with completion_lock if there was a linked timeout.

Cc: stable@vger.kernel.org # 5.9+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/93f7c617e2b4f012a2a175b3dab6bc2f27cebc48.1627304436.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-07-26 14:14:31 +01:00 committed by Jens Axboe
parent 991468dcf1
commit 44eff40a32
1 changed files with 11 additions and 2 deletions
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13
fs/io_uring.c
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@ -1279,8 +1279,17 @@ static void io_prep_async_link(struct io_kiocb *req)
{
struct io_kiocb *cur;
io_for_each_link(cur, req)
io_prep_async_work(cur);
if (req->flags & REQ_F_LINK_TIMEOUT) {
struct io_ring_ctx *ctx = req->ctx;
spin_lock_irq(&ctx->completion_lock);
io_for_each_link(cur, req)
io_prep_async_work(cur);
spin_unlock_irq(&ctx->completion_lock);
} else {
io_for_each_link(cur, req)
io_prep_async_work(cur);
}
}
static void io_queue_async_work(struct io_kiocb *req)