4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet <edumazet@xxxxxxxxxx> 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@xxxxxxxxxx> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/net/nexthop.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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; }