| Message ID | 20240822001707.2116-4-pablo@netfilter.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,1/3] netfilter: nft_counter: Disable BH in nft_counter_offload_stats(). | expand |
On Thu, Aug 22, 2024 at 2:17 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote: > > 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: 4cd91f7c290f ("netfilter: flowtable: add vlan support") > Reported-by: syzbot+8407d9bb88cd4c6bf61a@syzkaller.appspotmail.com > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> > --- > net/netfilter/nf_flow_table_inet.c | 3 +++ > net/netfilter/nf_flow_table_ip.c | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/net/netfilter/nf_flow_table_inet.c b/net/netfilter/nf_flow_table_inet.c > index 88787b45e30d..dd9a392052ee 100644 > --- a/net/netfilter/nf_flow_table_inet.c > +++ b/net/netfilter/nf_flow_table_inet.c > @@ -17,6 +17,9 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb, > > switch (skb->protocol) { > case htons(ETH_P_8021Q): > + if (!pskb_may_pull(skb, VLAN_HLEN)) > + return NF_ACCEPT; > + > veth = (struct vlan_ethhdr *)skb_mac_header(skb); Is skb_mac_header(skb) always pointing at skb->data - 14 at this stage ? Otherwise, using if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)) would be safer.
On Thu, Aug 22, 2024 at 08:39:56AM +0200, Eric Dumazet wrote: > On Thu, Aug 22, 2024 at 2:17 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote: > > > > 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: 4cd91f7c290f ("netfilter: flowtable: add vlan support") > > Reported-by: syzbot+8407d9bb88cd4c6bf61a@syzkaller.appspotmail.com > > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> > > --- > > net/netfilter/nf_flow_table_inet.c | 3 +++ > > net/netfilter/nf_flow_table_ip.c | 3 +++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/net/netfilter/nf_flow_table_inet.c b/net/netfilter/nf_flow_table_inet.c > > index 88787b45e30d..dd9a392052ee 100644 > > --- a/net/netfilter/nf_flow_table_inet.c > > +++ b/net/netfilter/nf_flow_table_inet.c > > @@ -17,6 +17,9 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb, > > > > switch (skb->protocol) { > > case htons(ETH_P_8021Q): > > + if (!pskb_may_pull(skb, VLAN_HLEN)) > > + return NF_ACCEPT; > > + > > veth = (struct vlan_ethhdr *)skb_mac_header(skb); > > Is skb_mac_header(skb) always pointing at skb->data - 14 at this stage ? > > Otherwise, using > > if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)) would be safer. That looks consistent. Done and I just sent a new PR. Thanks.
diff --git a/net/netfilter/nf_flow_table_inet.c b/net/netfilter/nf_flow_table_inet.c index 88787b45e30d..dd9a392052ee 100644 --- a/net/netfilter/nf_flow_table_inet.c +++ b/net/netfilter/nf_flow_table_inet.c @@ -17,6 +17,9 @@ nf_flow_offload_inet_hook(void *priv, struct sk_buff *skb, switch (skb->protocol) { case htons(ETH_P_8021Q): + if (!pskb_may_pull(skb, VLAN_HLEN)) + return NF_ACCEPT; + veth = (struct vlan_ethhdr *)skb_mac_header(skb); proto = veth->h_vlan_encapsulated_proto; break; diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c index c2c005234dcd..9a9031e9ea1c 100644 --- a/net/netfilter/nf_flow_table_ip.c +++ b/net/netfilter/nf_flow_table_ip.c @@ -281,6 +281,9 @@ static bool nf_flow_skb_encap_protocol(struct sk_buff *skb, __be16 proto, switch (skb->protocol) { case htons(ETH_P_8021Q): + if (!pskb_may_pull(skb, VLAN_HLEN)) + return false; + veth = (struct vlan_ethhdr *)skb_mac_header(skb); if (veth->h_vlan_encapsulated_proto == proto) { *offset += VLAN_HLEN;
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: 4cd91f7c290f ("netfilter: flowtable: add vlan support") Reported-by: syzbot+8407d9bb88cd4c6bf61a@syzkaller.appspotmail.com Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> --- net/netfilter/nf_flow_table_inet.c | 3 +++ net/netfilter/nf_flow_table_ip.c | 3 +++ 2 files changed, 6 insertions(+)