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netfilter: flowtable: validate vlan header

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Ensure there is sufficient room to access the protocol field of the
VLAN header, validate it once before the flowtable lookup.

=====================================================
BUG: KMSAN: uninit-value in nf_flow_offload_inet_hook+0x45a/0x5f0 net/netfilter/nf_flow_table_inet.c:32
 nf_flow_offload_inet_hook+0x45a/0x5f0 net/netfilter/nf_flow_table_inet.c:32
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626
 nf_hook_ingress include/linux/netfilter_netdev.h:34 [inline]
 nf_ingress net/core/dev.c:5440 [inline]

Fixes: 4cd91f7c29 ("netfilter: flowtable: add vlan support")
Reported-by: syzbot+8407d9bb88cd4c6bf61a@syzkaller.appspotmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2024-08-13 12:39:46 +02:00
parent a0b39e2dc7
commit 6ea14ccb60
2 changed files with 6 additions and 0 deletions
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3
net/netfilter/nf_flow_table_inet.c
View File

@ -17,6 +17,9 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb,
switch (skb->protocol) { switch (skb->protocol) {
case htons(ETH_P_8021Q): case htons(ETH_P_8021Q):
if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)))
return NF_ACCEPT;
veth = (struct vlan_ethhdr *)skb_mac_header(skb); veth = (struct vlan_ethhdr *)skb_mac_header(skb);
proto = veth->h_vlan_encapsulated_proto; proto = veth->h_vlan_encapsulated_proto;
break; break;

3
net/netfilter/nf_flow_table_ip.c
View File

@ -281,6 +281,9 @@ static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto,
switch (skb->protocol) { switch (skb->protocol) {
case htons(ETH_P_8021Q): case htons(ETH_P_8021Q):
if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)))
return false;
veth = (struct vlan_ethhdr *)skb_mac_header(skb); veth = (struct vlan_ethhdr *)skb_mac_header(skb);
if (veth->h_vlan_encapsulated_proto == proto) { if (veth->h_vlan_encapsulated_proto == proto) {
*offset += VLAN_HLEN; *offset += VLAN_HLEN;