CVE-2024-40957

In the Linux kernel, the following vulnerability has been resolved:

seg6: fix parameter passing when calling NF_HOOK() in End.DX4 and End.DX6 behaviors

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;

}