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io_uring: terminate manual loop iterator loop correctly for non-vecs

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[ Upstream commit 5e929367468c8f97cd1ffb0417316cecfebef94b ]

The fix for not advancing the iterator if we're using fixed buffers is
broken in that it can hit a condition where we don't terminate the loop.
This results in io-wq looping forever, asking to read (or write) 0 bytes
for every subsequent loop.

Reported-by: Joel Jaeschke <joel.jaeschke@gmail.com>
Link: https://github.com/axboe/liburing/issues/549
Fixes: 16c8d2df7ec0 ("io_uring: ensure symmetry in handling iter types in loop_rw_iter()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jens Axboe 2022-03-18 11:28:13 -06:00 committed by Greg Kroah-Hartman
parent 44a77e52bd
commit 509565faed
1 changed files with 4 additions and 2 deletions
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6
fs/io_uring.c
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@ -3220,13 +3220,15 @@ static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
ret = nr;
break;
}
ret += nr;
if (!iov_iter_is_bvec(iter)) {
iov_iter_advance(iter, nr);
} else {
req->rw.len -= nr;
req->rw.addr += nr;
req->rw.len -= nr;
if (!req->rw.len)
break;
}
ret += nr;
if (nr != iovec.iov_len)
break;
}