net: nexthop: fix percpu use-after-free in remove_nh_grp_entry

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Summary

CVECVE-2026-43374
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 15:16:48 UTC
Updated2026-05-08 15:16:48 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f4676ea74b8549cd88dbfe2a592ce4530039e61f abf4feaee6405f1441929c6ebe7a250f2cd170a7 git Not specified
CNA Linux Linux affected f4676ea74b8549cd88dbfe2a592ce4530039e61f ab5ebab9664214ba41a7633cb4e72f128204f924 git Not specified
CNA Linux Linux affected f4676ea74b8549cd88dbfe2a592ce4530039e61f 9e08ad731862b22a87cc55f752e16d66cdc9e231 git Not specified
CNA Linux Linux affected f4676ea74b8549cd88dbfe2a592ce4530039e61f b2662e7593e94ae09b1cf7ee5f09160a3612bcb2 git Not specified
CNA Linux Linux affected 6.9 Not specified
CNA Linux Linux unaffected 6.9 semver Not specified
CNA Linux Linux unaffected 6.12.78 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.19 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.9 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b2662e7593e94ae09b1cf7ee5f09160a3612bcb2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ab5ebab9664214ba41a7633cb4e72f128204f924 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9e08ad731862b22a87cc55f752e16d66cdc9e231 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/abf4feaee6405f1441929c6ebe7a250f2cd170a7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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