From: Eric Dumazet <edumazet@google.com>
Date: Sat, 7 Apr 2018 20:42:38 +0000 (-0700)
Subject: net: fix rtnh_ok()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ced9763b911d66ab4da4a9edf2a8d3ce29238af8;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.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 36bb794f5cd6..902ff382a6dc 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -7,7 +7,7 @@
 
 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;
 }