releases/4.9.26/kcm-return-immediately-after-copy_from_user-failure.patch

From foo@baz Sat Apr 29 08:22:13 CEST 2017
From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Thu, 23 Mar 2017 11:03:31 -0700
Subject: kcm: return immediately after copy_from_user() failure

From: WANG Cong <xiyou.wangcong@gmail.com>


[ Upstream commit a80db69e47d764bbcaf2fec54b1f308925e7c490 ]

There is no reason to continue after a copy_from_user()
failure.

Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/kcm/kcmsock.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1685,7 +1685,7 @@ static int kcm_ioctl(struct socket *sock
 		struct kcm_attach info;
 
 		if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
-			err = -EFAULT;
+			return -EFAULT;
 
 		err = kcm_attach_ioctl(sock, &info);
 
@@ -1695,7 +1695,7 @@ static int kcm_ioctl(struct socket *sock
 		struct kcm_unattach info;
 
 		if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
-			err = -EFAULT;
+			return -EFAULT;
 
 		err = kcm_unattach_ioctl(sock, &info);
 
@@ -1706,7 +1706,7 @@ static int kcm_ioctl(struct socket *sock
 		struct socket *newsock = NULL;
 
 		if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
-			err = -EFAULT;
+			return -EFAULT;
 
 		err = kcm_clone(sock, &info, &newsock);