From e3bb847cc46cfe70e4e45834eba426b2449d79e3 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 7 Jan 2021 07:45:06 +0000
Subject: [PATCH] io_uring: fix 0-iov read buffer select

stable inclusion
from stable-5.10.4
commit 72a016d42d3611ee13eb1e0c943b7397f21f7b62
bugzilla: 46903

--------------------------------

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>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
---
 fs/io_uring.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index c422f255b51b..797874f215b1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3048,9 +3048,7 @@ static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
 		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
-- 
GitLab