From: Guillaume Nault gnault@redhat.com
mainline inclusion from mainline-v5.13-rc6 commit da5a2e49f064a86a3b102b20c545f855a7298394 category: bugfix bugzilla: 189707, https://gitee.com/src-openeuler/kernel/issues/I99JV2 CVE: CVE-2024-26641
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Reset the mac_header pointer even when the tunnel transports only L3 data (in the ARPHRD_ETHER case, this is already done by eth_type_trans). This prevents other parts of the stack from mistakenly accessing the outer header after the packet has been decapsulated.
In practice, this allows to push an Ethernet header to ipip6, ip6ip6, mplsip6 or ip6gre packets and redirect them to an Ethernet device:
$ tc filter add dev ip6tnl0 ingress matchall \ action vlan push_eth dst_mac 00:00:5e:00:53:01 \ src_mac 00:00:5e:00:53:00 \ action mirred egress redirect dev eth0
Without this patch, push_eth refuses to add an ethernet header because the skb appears to already have a MAC header.
Signed-off-by: Guillaume Nault gnault@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Dong Chenchen dongchenchen2@huawei.com --- net/ipv6/ip6_tunnel.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index e4592a53bd30..58e7f8122efa 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -817,6 +817,7 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN); } else { skb->dev = tunnel->dev; + skb_reset_mac_header(skb); }
skb_reset_network_header(skb);