CVE-2024-56647

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

net: Fix icmp host relookup triggering ip_rt_bug

arp link failure may trigger ip_rt_bug while xfrm enabled, call trace is:

WARNING: CPU: 0 PID: 0 at net/ipv4/route.c:1241 ip_rt_bug+0x14/0x20

Modules linked in:

CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc6-00077-g2e1b3cc9d7f7

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),

BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014

RIP: 0010:ip_rt_bug+0x14/0x20

Call Trace:

<IRQ>

ip_send_skb+0x14/0x40

__icmp_send+0x42d/0x6a0

ipv4_link_failure+0xe2/0x1d0

arp_error_report+0x3c/0x50

neigh_invalidate+0x8d/0x100

neigh_timer_handler+0x2e1/0x330

call_timer_fn+0x21/0x120

__run_timer_base.part.0+0x1c9/0x270

run_timer_softirq+0x4c/0x80

handle_softirqs+0xac/0x280

irq_exit_rcu+0x62/0x80

sysvec_apic_timer_interrupt+0x77/0x90

The script below reproduces this scenario:

ip xfrm policy add src 0.0.0.0/0 dst 0.0.0.0/0 \

dir out priority 0 ptype main flag localok icmp

ip l a veth1 type veth

ip a a 192.168.141.111/24 dev veth0

ip l s veth0 up

ping 192.168.141.155 -c 1

icmp_route_lookup() create input routes for locally generated packets

while xfrm relookup ICMP traffic.Then it will set input route

(dst->out = ip_rt_bug) to skb for DESTUNREACH.

For ICMP err triggered by locally generated packets, dst->dev of output

route is loopback. Generally, xfrm relookup verification is not required

on loopback interfaces (net.ipv4.conf.lo.disable_xfrm = 1).

Skip icmp relookup for locally generated packets to fix it.