3.16.50-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Julian Wiedmann <jwi@xxxxxxxxxxxxxxxxxx> commit ec2c6726322f0d270bab477e4904bf9496f70ee5 upstream. On L3, the qeth_hdr struct needs to be filled with the next-hop IP address. The current code accesses rtable->rt_gateway without checking that rtable is a valid address. The accidental access to a lowcore area results in a random next-hop address in the qeth_hdr. rtable (or more precisely, skb_dst(skb)) can be NULL in rare cases (for instance together with AF_PACKET sockets). This patch adds the missing NULL-ptr checks. Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxxxxxxx> Signed-off-by: Ursula Braun <ubraun@xxxxxxxxxxxxxxxxxx> Fixes: 87e7597b5a3 qeth: Move away from using neighbour entries in qeth_l3_fill_header() Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/s390/net/qeth_l3_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -2816,7 +2816,7 @@ static void qeth_l3_fill_header(struct q struct rtable *rt = (struct rtable *) dst; __be32 *pkey = &ip_hdr(skb)->daddr; - if (rt->rt_gateway) + if (rt && rt->rt_gateway) pkey = &rt->rt_gateway; /* IPv4 */ @@ -2827,7 +2827,7 @@ static void qeth_l3_fill_header(struct q struct rt6_info *rt = (struct rt6_info *) dst; struct in6_addr *pkey = &ipv6_hdr(skb)->daddr; - if (!ipv6_addr_any(&rt->rt6i_gateway)) + if (rt && !ipv6_addr_any(&rt->rt6i_gateway)) pkey = &rt->rt6i_gateway; /* IPv6 */