3.18-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 1dfe82ebd7d8fd43dba9948fdfb31f145014baa0 ]
skb mac header is not necessarily set at the time skb_network_protocol() is called. Use skb->data instead.
BUG: KASAN: slab-out-of-bounds in skb_network_protocol+0x46b/0x4b0 net/core/dev.c:2739 Read of size 2 at addr ffff8801b3097a0b by task syz-executor5/14242
CPU: 1 PID: 14242 Comm: syz-executor5 Not tainted 4.16.0-rc6+ #280 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23c/0x360 mm/kasan/report.c:412 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:443 skb_network_protocol+0x46b/0x4b0 net/core/dev.c:2739 harmonize_features net/core/dev.c:2924 [inline] netif_skb_features+0x509/0x9b0 net/core/dev.c:3011 validate_xmit_skb+0x81/0xb00 net/core/dev.c:3084 validate_xmit_skb_list+0xbf/0x120 net/core/dev.c:3142 packet_direct_xmit+0x117/0x790 net/packet/af_packet.c:256 packet_snd net/packet/af_packet.c:2944 [inline] packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2969 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xca/0x110 net/socket.c:639 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2047 __sys_sendmsg+0xe5/0x210 net/socket.c:2081
Fixes: 19acc327258a ("gso: Handle Trans-Ether-Bridging protocol in skb_network_protocol()") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Pravin B Shelar pshelar@ovn.org Reported-by: Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/core/dev.c +++ b/net/core/dev.c @@ -2372,7 +2372,7 @@ __be16 skb_network_protocol(struct sk_bu if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr)))) return 0;
- eth = (struct ethhdr *)skb_mac_header(skb); + eth = (struct ethhdr *)skb->data; type = eth->h_proto; }