commit d60d4e8c1b73608b6af3bc384e88c062485fd95e
author WANG Cong <xiyou.wangcong@gmail.com> Thu Mar 23 11:03:31 2017 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> Wed May 03 08:36:34 2017 -0700
tree f47b006a7304e7323bfc9b218d02bfdd718df1ac
parent c63d6180076bbb6c5a508910e573994ddc628e5b

kcm: return immediately after copy_from_user() failure

[ 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

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index a646f34..fecad10 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1685,7 +1685,7 @@
 		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 @@
 		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 @@
 		struct socket *newsock = NULL;
 
 		if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
-			err = -EFAULT;
+			return -EFAULT;
 
 		err = kcm_clone(sock, &info, &newsock);