{"cve":"CVE-2026-64418","nvd":{"published":"2026-07-25T10:17:25.727","modified":"2026-09-04T15:24:49.577","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: shrinker: fix shrinker_info teardown race with expansion\n\nexpand_shrinker_info() iterates all visible memcgs under shrinker_mutex,\nincluding memcgs that have not finished ->css_online() yet.\n\nOnce pn->shrinker_info has been published, teardown must stay serialized\nwith expand_shrinker_info() until that memcg is either fully online or no\nlonger visible to iteration.  Today alloc_shrinker_info() breaks that rule\nby dropping shrinker_mutex before freeing a partially initialized\nshrinker_info array, which may cause the following race:\n\nCPU0                   CPU1\n====                   ====\n\ncss_create\n--> list_add_tail_rcu(&css->sibling, &parent_css->children);\n    online_css\n    --> mem_cgroup_css_online\n        --> alloc_shrinker_info\n            --> alloc node0 info\n                rcu_assign_pointer(C->node0->shrinker_info, old0)\n                alloc node1 info -> FAIL -> goto err\n                mutex_unlock(shrinker_mutex)\n\n                       shrinker_alloc()\n                       --> shrinker_memcg_alloc\n                           --> mutex_lock(shrinker_mutex)\n                               expand_shrinker_info\n                               --> mem_cgroup_iter see the memcg\n                                   expand_one_shrinker_info\n                                   --> old0 = C->node0->shrinker_info\n                                       memcpy(new->unit, old0->unit, ...);\n\n                free_shrinker_info\n                --> kvfree(old0);\n\n                                       /* double free !! */\n                                       kvfree_rcu(old0, rcu);\n\nThe same problem exists later in mem_cgroup_css_online().  If\nalloc_shrinker_info() succeeds but a subsequent objcg allocation fails,\nthe free_objcg -> free_shrinker_info() unwind path tears down the already\npublished pn->shrinker_info arrays without shrinker_mutex.  The\nexpand_one_shrinker_info() can race with that teardown in the same way,\nleading to use-after-free or double-free of the old shrinker_info.\n\nFix this by serializing shrinker_info teardown with shrinker_mutex, and by\nkeeping alloc_shrinker_info() error cleanup inside the locked section.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/284c267f013e45d8c89d9fb9373105dc8e6c0947","https://git.kernel.org/stable/c/6465ff3ce65131c774a312d450abe10f4b9f3875","https://git.kernel.org/stable/c/65476d31d8056e859c48580f82295ce159196ffe","https://git.kernel.org/stable/c/b9a280a9a454ed514636351d53fe2a233dc5054b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:46:40.600842820+00:00"},"epss":{"cve":"CVE-2026-64418","score":0.00097,"percentile":0.00696,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}