From: Florian Westphal fw@strlen.de
[ Upstream commit 5648b5e1169ff1d6d6a46c35c0b5fbebd2a5cbb2 ]
On 64bit platforms the MAC header is set to 0xffff on allocation and also when a helper like skb_unset_mac_header() is called.
dev_parse_header may call skb_mac_header() which assumes valid mac offset:
BUG: KASAN: use-after-free in eth_header_parse+0x75/0x90 Read of size 6 at addr ffff8881075a5c05 by task nf-queue/1364 Call Trace: memcpy+0x20/0x60 eth_header_parse+0x75/0x90 __nfqnl_enqueue_packet+0x1a61/0x3380 __nf_queue+0x597/0x1300 nf_queue+0xf/0x40 nf_hook_slow+0xed/0x190 nf_hook+0x184/0x440 ip_output+0x1c0/0x2a0 nf_reinject+0x26f/0x700 nfqnl_recv_verdict+0xa16/0x18b0 nfnetlink_rcv_msg+0x506/0xe70
The existing code only works if the skb has a mac header.
Fixes: 2c38de4c1f8da7 ("netfilter: fix looped (broad|multi)cast's MAC handling") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nfnetlink_queue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 54cde78c27183..ebce25080f7ff 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -486,7 +486,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, goto nla_put_failure;
if (indev && entskb->dev && - entskb->mac_header != entskb->network_header) { + skb_mac_header_was_set(entskb)) { struct nfqnl_msg_packet_hw phw; int len;