From 109dda45102112799e507a65e375ebb096d3ae49 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 18 Mar 2022 11:28:13 -0600
Subject: [PATCH] io_uring: terminate manual loop iterator loop correctly for
non-vecs
[ 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>
---
fs/io_uring.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 70e85f64dc389..ec0b50940405f 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3319,13 +3319,15 @@ 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;
}
--
2.30.2