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.
How to fix
- linux linux_kernel6.12.78, 6.18.19, 6.19.9 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| linux linux_kernel | 6.9 ≤ v < 6.12.78, 6.13 ≤ v < 6.18.19, 6.19 ≤ v < 6.19.9, 6.9, 7.0 | 6.12.78, 6.18.19, 6.19.9 |
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