CVE-2026-23304

In the Linux kernel, the following vulnerability has been resolved: ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu() l3mdev_master_dev_rcu() can return NULL when the slave device is being un-slaved from a VRF. All other callers deal with this, but we lost the fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu() with commit 4832c30d5458 ("net: ipv6: put host and anycast routes on device with address"). KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418) Call Trace: ip6_pol_route (net/ipv6/route.c:2318) fib6_rule_lookup (net/ipv6/fib6_rules.c:115) ip6_route_output_flags (net/ipv6/route.c:2607) vrf_process_v6_outbound (drivers/net/vrf.c:437) I was tempted to rework the un-slaving code to clear the flag first and insert synchronize_rcu() before we remove the upper. But looks like the explicit fallback to loopback_dev is an established pattern. And I guess avoiding the synchronize_rcu() is nice, too.

• linux linux kernel (>= 4.14 < 5.10.253) • linux linux kernel (>= 5.11 < 5.15.203) • linux linux kernel (>= 5.16 < 6.1.167) • linux linux kernel (>= 6.2 < 6.6.130) • linux linux kernel (>= 6.7 < 6.12.77) • linux linux kernel (>= 6.13 < 6.18.17) • linux linux kernel (>= 6.19 < 6.19.7) • linux linux kernel 7.0