CVE-2026-43374

Description

In the Linux kernel, the following vulnerability has been resolved: net: nexthop: fix percpu use-after-free in remove_nh_grp_entry When removing a nexthop from a group, remove_nh_grp_entry() publishes the new group via rcu_assign_pointer() then immediately frees the removed entry's percpu stats with free_percpu(). However, the synchronize_net() grace period in the caller remove_nexthop_from_groups() runs after the free. RCU readers that entered before the publish still see the old group and can dereference the freed stats via nh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a use-after-free on percpu memory. Fix by deferring the free_percpu() until after synchronize_net() in the caller. Removed entries are chained via nh_list onto a local deferred free list. After the grace period completes and all RCU readers have finished, the percpu stats are safely freed.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

References

• https://git.kernel.org/stable/c/abf4feaee6405f1441929c6ebe7a250f2cd170a7 ↗
• https://git.kernel.org/stable/c/ab5ebab9664214ba41a7633cb4e72f128204f924 ↗
• https://git.kernel.org/stable/c/9e08ad731862b22a87cc55f752e16d66cdc9e231 ↗
• https://git.kernel.org/stable/c/b2662e7593e94ae09b1cf7ee5f09160a3612bcb2 ↗