From: Jianguo Wu <wujianguo@xxxxxxxxxxxxxxx>
input_action_end_dx4() and input_action_end_dx6() are called NF_HOOK() for
PREROUTING hook, in PREROUTING hook, we should passing a valid indev,
and a NULL outdev to NF_HOOK(), otherwise may trigger a NULL pointer
dereference, as below:
[74830.647293] BUG: kernel NULL pointer dereference, address: 0000000000000090
[74830.655633] #PF: supervisor read access in kernel mode
[74830.657888] #PF: error_code(0x0000) - not-present page
[74830.659500] PGD 0 P4D 0
[74830.660450] Oops: 0000 [#1] PREEMPT SMP PTI
...
[74830.664953] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[74830.666569] RIP: 0010:rpfilter_mt+0x44/0x15e [ipt_rpfilter]
...
[74830.689725] Call Trace:
[74830.690402] <IRQ>
[74830.690953] ? show_trace_log_lvl+0x1c4/0x2df
[74830.692020] ? show_trace_log_lvl+0x1c4/0x2df
[74830.693095] ? ipt_do_table+0x286/0x710 [ip_tables]
[74830.694275] ? __die_body.cold+0x8/0xd
[74830.695205] ? page_fault_oops+0xac/0x140
[74830.696244] ? exc_page_fault+0x62/0x150
[74830.697225] ? asm_exc_page_fault+0x22/0x30
[74830.698344] ? rpfilter_mt+0x44/0x15e [ipt_rpfilter]
[74830.699540] ipt_do_table+0x286/0x710 [ip_tables]
[74830.700758] ? ip6_route_input+0x19d/0x240
[74830.701752] nf_hook_slow+0x3f/0xb0
[74830.702678] input_action_end_dx4+0x19b/0x1e0
[74830.703735] ? input_action_end_t+0xe0/0xe0
[74830.704734] seg6_local_input_core+0x2d/0x60
[74830.705782] lwtunnel_input+0x5b/0xb0
[74830.706690] __netif_receive_skb_one_core+0x63/0xa0
[74830.707825] process_backlog+0x99/0x140
[74830.709538] __napi_poll+0x2c/0x160
[74830.710673] net_rx_action+0x296/0x350
[74830.711860] __do_softirq+0xcb/0x2ac
[74830.713049] do_softirq+0x63/0x90
input_action_end_dx4() passing a NULL indev to NF_HOOK(), and finally
trigger a NULL dereference in rpfilter_mt()->rpfilter_is_loopback():
static bool
rpfilter_is_loopback(const struct sk_buff *skb,
const struct net_device *in)
{
// in is NULL
return skb->pkt_type == PACKET_LOOPBACK ||
in->flags & IFF_LOOPBACK;
}
Fixes: 7a3f5b0de364 ("netfilter: add netfilter hooks to SRv6 data plane")
Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/ipv6/seg6_local.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index 24e2b4b494cb..c434940131b1 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -941,8 +941,8 @@ static int input_action_end_dx6(struct sk_buff *skb,
if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
- dev_net(skb->dev), NULL, skb, NULL,
- skb_dst(skb)->dev, input_action_end_dx6_finish);
+ dev_net(skb->dev), NULL, skb, skb->dev,
+ NULL, input_action_end_dx6_finish);
return input_action_end_dx6_finish(dev_net(skb->dev), NULL, skb);
drop:
@@ -991,8 +991,8 @@ static int input_action_end_dx4(struct sk_buff *skb,
if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
- dev_net(skb->dev), NULL, skb, NULL,
- skb_dst(skb)->dev, input_action_end_dx4_finish);
+ dev_net(skb->dev), NULL, skb, skb->dev,
+ NULL, input_action_end_dx4_finish);
return input_action_end_dx4_finish(dev_net(skb->dev), NULL, skb);
drop:
--
2.30.2
