[PATCH 5.10 517/717] io_uring: fix 0-iov read buffer select

Greg Kroah-Hartman
2020-12-28T14:25:30Z

From: Pavel Begunkov <asml.silence@gmail.com>

commit dd20166236953c8cd14f4c668bf972af32f0c6be upstream.

Doing vectored buf-select read with 0 iovec passed is meaningless and
utterly broken, forbid it.

Cc: <stable@vger.kernel.org> # 5.7+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/io_uring.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3048,9 +3048,7 @@ static ssize_t io_iov_buffer_select(stru
iov[0].iov_len = kbuf->len;
return 0;
}
- if (!req->rw.len)
- return 0;
- else if (req->rw.len > 1)
+ if (req->rw.len != 1)
return -EINVAL;

#ifdef CONFIG_COMPAT