linux-kernel - [PATCH] fs: Return -EFAULT if copy_to

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Date:   Mon,  1 Mar 2021 19:26:00 +0800
From:   Wang Qing <wangqing@...o.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] fs: Return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 fs/select.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/select.c b/fs/select.c
index 37aaa83..93cd35b
--- a/fs/select.c
+++ b/fs/select.c
@@ -400,7 +400,7 @@ static inline unsigned long __must_check
 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 {
 	if (ufdset)
-		return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
+		return __copy_to_user(ufdset, fdset, FDS_BYTES(nr)) ? -EFAULT : 0;
 	return 0;
 }
 
-- 
2.7.4