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io_uring: fix racy IOPOLL completions

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IOPOLL allows buffer remove/provide requests, but they doesn't
synchronise by rules of IOPOLL, namely it have to hold uring_lock.

Cc: <stable@vger.kernel.org> # 5.7+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-12-06 22:22:43 +00:00 committed by Jens Axboe
parent dad1b1242f
commit 31bff9a51b
1 changed files with 18 additions and 5 deletions
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23
fs/io_uring.c
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@ -4152,11 +4152,17 @@ static int io_remove_buffers(struct io_kiocb *req, bool force_nonblock,
head = idr_find(&ctx->io_buffer_idr, p->bgid);
if (head)
ret = __io_remove_buffers(ctx, head, p->bgid, p->nbufs);
io_ring_submit_lock(ctx, !force_nonblock);
if (ret < 0)
req_set_fail_links(req);
__io_req_complete(req, ret, 0, cs);
/* need to hold the lock to complete IOPOLL requests */
if (ctx->flags & IORING_SETUP_IOPOLL) {
__io_req_complete(req, ret, 0, cs);
io_ring_submit_unlock(ctx, !force_nonblock);
} else {
io_ring_submit_unlock(ctx, !force_nonblock);
__io_req_complete(req, ret, 0, cs);
}
return 0;
}
@ -4241,10 +4247,17 @@ static int io_provide_buffers(struct io_kiocb *req, bool force_nonblock,
}
}
out:
io_ring_submit_unlock(ctx, !force_nonblock);
if (ret < 0)
req_set_fail_links(req);
__io_req_complete(req, ret, 0, cs);
/* need to hold the lock to complete IOPOLL requests */
if (ctx->flags & IORING_SETUP_IOPOLL) {
__io_req_complete(req, ret, 0, cs);
io_ring_submit_unlock(ctx, !force_nonblock);
} else {
io_ring_submit_unlock(ctx, !force_nonblock);
__io_req_complete(req, ret, 0, cs);
}
return 0;
}