CVE-2024-56647

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: Fix icmp host relookup triggering ip_rt_bug<br /> <br /> arp link failure may trigger ip_rt_bug while xfrm enabled, call trace is:<br /> <br /> WARNING: CPU: 0 PID: 0 at net/ipv4/route.c:1241 ip_rt_bug+0x14/0x20<br /> Modules linked in:<br /> CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc6-00077-g2e1b3cc9d7f7<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),<br /> BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014<br /> RIP: 0010:ip_rt_bug+0x14/0x20<br /> Call Trace:<br /> <br /> ip_send_skb+0x14/0x40<br /> __icmp_send+0x42d/0x6a0<br /> ipv4_link_failure+0xe2/0x1d0<br /> arp_error_report+0x3c/0x50<br /> neigh_invalidate+0x8d/0x100<br /> neigh_timer_handler+0x2e1/0x330<br /> call_timer_fn+0x21/0x120<br /> __run_timer_base.part.0+0x1c9/0x270<br /> run_timer_softirq+0x4c/0x80<br /> handle_softirqs+0xac/0x280<br /> irq_exit_rcu+0x62/0x80<br /> sysvec_apic_timer_interrupt+0x77/0x90<br /> <br /> The script below reproduces this scenario:<br /> ip xfrm policy add src 0.0.0.0/0 dst 0.0.0.0/0 \<br /> dir out priority 0 ptype main flag localok icmp<br /> ip l a veth1 type veth<br /> ip a a 192.168.141.111/24 dev veth0<br /> ip l s veth0 up<br /> ping 192.168.141.155 -c 1<br /> <br /> icmp_route_lookup() create input routes for locally generated packets<br /> while xfrm relookup ICMP traffic.Then it will set input route<br /> (dst-&gt;out = ip_rt_bug) to skb for DESTUNREACH.<br /> <br /> For ICMP err triggered by locally generated packets, dst-&gt;dev of output<br /> route is loopback. Generally, xfrm relookup verification is not required<br /> on loopback interfaces (net.ipv4.conf.lo.disable_xfrm = 1).<br /> <br /> Skip icmp relookup for locally generated packets to fix it.