From: Eric Dumazet <edumazet@google.com>
Date: Sat, 7 Apr 2018 20:42:38 +0000 (-0700)
Subject: net: fix rtnh_ok()
X-Git-Tag: v4.9.100~31
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a3cac7e26bbd944cc8bfc96c81d6784fbde594ec;p=platform%2Fkernel%2Flinux-amlogic.git

net: fix rtnh_ok()

commit b1993a2de12c9e75c35729e2ffbc3a92d50c0d31 upstream.

syzbot reported :

BUG: KMSAN: uninit-value in rtnh_ok include/net/nexthop.h:11 [inline]
BUG: KMSAN: uninit-value in fib_count_nexthops net/ipv4/fib_semantics.c:469 [inline]
BUG: KMSAN: uninit-value in fib_create_info+0x554/0x8d20 net/ipv4/fib_semantics.c:1091

@remaining is an integer, coming from user space.
If it is negative we want rtnh_ok() to return false.

Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 3334dbfa5aa4..7fc78663ec9d 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -6,7 +6,7 @@
 
 static inline int rtnh_ok(const struct rtnexthop *rtnh, int remaining)
 {
-	return remaining >= sizeof(*rtnh) &&
+	return remaining >= (int)sizeof(*rtnh) &&
 	       rtnh->rtnh_len >= sizeof(*rtnh) &&
 	       rtnh->rtnh_len <= remaining;
 }