CVE-2024-33621

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

ipvlan: Dont Use skb->sk in ipvlan_process_v{4,6}_outbound

Raw packet from PF_PACKET socket ontop of an IPv6-backed ipvlan device will

hit WARN_ON_ONCE() in sk_mc_loop() through sch_direct_xmit() path.

WARNING: CPU: 2 PID: 0 at net/core/sock.c:775 sk_mc_loop+0x2d/0x70

Modules linked in: sch_netem ipvlan rfkill cirrus drm_shmem_helper sg drm_kms_helper

CPU: 2 PID: 0 Comm: swapper/2 Kdump: loaded Not tainted 6.9.0+ #279

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

RIP: 0010:sk_mc_loop+0x2d/0x70

Code: fa 0f 1f 44 00 00 65 0f b7 15 f7 96 a3 4f 31 c0 66 85 d2 75 26 48 85 ff 74 1c

RSP: 0018:ffffa9584015cd78 EFLAGS: 00010212

RAX: 0000000000000011 RBX: ffff91e585793e00 RCX: 0000000002c6a001

RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff91e589c0f000

RBP: ffff91e5855bd100 R08: 0000000000000000 R09: 3d00545216f43d00

R10: ffff91e584fdcc50 R11: 00000060dd8616f4 R12: ffff91e58132d000

R13: ffff91e584fdcc68 R14: ffff91e5869ce800 R15: ffff91e589c0f000

FS: 0000000000000000(0000) GS:ffff91e898100000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f788f7c44c0 CR3: 0000000008e1a000 CR4: 00000000000006f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

<IRQ>

? __warn (kernel/panic.c:693)

? sk_mc_loop (net/core/sock.c:760)

? report_bug (lib/bug.c:201 lib/bug.c:219)

? handle_bug (arch/x86/kernel/traps.c:239)

? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))

? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)

? sk_mc_loop (net/core/sock.c:760)

ip6_finish_output2 (net/ipv6/ip6_output.c:83 (discriminator 1))

? nf_hook_slow (net/netfilter/core.c:626)

ip6_finish_output (net/ipv6/ip6_output.c:222)

? __pfx_ip6_finish_output (net/ipv6/ip6_output.c:215)

ipvlan_xmit_mode_l3 (drivers/net/ipvlan/ipvlan_core.c:602) ipvlan

ipvlan_start_xmit (drivers/net/ipvlan/ipvlan_main.c:226) ipvlan

dev_hard_start_xmit (net/core/dev.c:3594)

sch_direct_xmit (net/sched/sch_generic.c:343)

__qdisc_run (net/sched/sch_generic.c:416)

net_tx_action (net/core/dev.c:5286)

handle_softirqs (kernel/softirq.c:555)

__irq_exit_rcu (kernel/softirq.c:589)

sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1043)

The warning triggers as this:

packet_sendmsg

packet_snd //skb->sk is packet sk

__dev_queue_xmit

__dev_xmit_skb //q->enqueue is not NULL

__qdisc_run

sch_direct_xmit

dev_hard_start_xmit

ipvlan_start_xmit

ipvlan_xmit_mode_l3 //l3 mode

ipvlan_process_outbound //vepa flag

ipvlan_process_v6_outbound

ip6_local_out

__ip6_finish_output

ip6_finish_output2 //multicast packet

sk_mc_loop //sk->sk_family is AF_PACKET

Call ip{6}_local_out() with NULL sk in ipvlan as other tunnels to fix this.