CVE-2026-64418 Detail
Received
This CVE record has recently been published to the CVE List and has been included within the NVD dataset. DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm: shrinker: fix shrinker_info teardown race with expansion expand_shrinker_info() iterates all visible memcgs under shrinker_mutex, including memcgs that have not finished ->css_online() yet. Once pn->shrinker_info has been published, teardown must stay serialized with expand_shrinker_info() until that memcg is either fully online or no longer visible to iteration. Today alloc_shrinker_info() breaks that rule by dropping shrinker_mutex before freeing a partially initialized shrinker_info array, which may cause the following race: CPU0 CPU1 ==== ==== css_create --> list_add_tail_rcu(&css->sibling, &parent_css->children); online_css --> mem_cgroup_css_online --> alloc_shrinker_info --> alloc node0 info rcu_assign_pointer(C->node0->shrinker_info, old0) alloc node1 info -> FAIL -> goto err mutex_unlock(shrinker_mutex) shrinker_alloc() --> shrinker_memcg_alloc --> mutex_lock(shrinker_mutex) expand_shrinker_info --> mem_cgroup_iter see the memcg expand_one_shrinker_info --> old0 = C->node0->shrinker_info memcpy(new->unit, old0->unit, ...); free_shrinker_info --> kvfree(old0); /* double free !! */ kvfree_rcu(old0, rcu); The same problem exists later in mem_cgroup_css_online(). If alloc_shrinker_info() succeeds but a subsequent objcg allocation fails, the free_objcg -> free_shrinker_info() unwind path tears down the already published pn->shrinker_info arrays without shrinker_mutex. The expand_one_shrinker_info() can race with that teardown in the same way, leading to use-after-free or double-free of the old shrinker_info. Fix this by serializing shrinker_info teardown with shrinker_mutex, and by keeping alloc_shrinker_info() error cleanup inside the locked section. Metrics
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Quick InfoCVE Dictionary Entry:CVE-2026-64418 NVD Published Date: 07/25/2026 NVD Last Modified: 07/25/2026 Source: kernel.org |
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