{"id":"CVE-2026-98225","revision":"7772b665b1904c0eba997a1723f57f8d","records":[{"revision":"7772b665b1904c0eba997a1723f57f8d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98225","aliases":[],"title":"mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem\n\nWith cgroup.memory=nokmem, shrinker_memcg_alloc() bails out early and\nnever allocates an id, so shrinker->id keeps the 0 it got from the\nkzalloc() in shrinker_alloc().  __list_lru_init() then copies that 0 into\nlru->shrinker_id, where it looks like a valid bit index.\n\nNothing calls expand_shrinker_info() on nokmem either, so shrinker_nr_max\nstays 0 and every memcg ends up with an empty map (map_nr_max == 0).\n\ndeferred_split_folio() hands a real memcg to __list_lru_add() regardless\nof whether the lru is memcg aware, so the first THP queued in a cgroup\ndoes set_shrinker_bit(memcg, nid, 0) and trips the bounds check:\n\nWARNING: mm/shrinker.c:212 at set_shrinker_bit+0x7d/0x90, CPU#126\nCall Trace:\n <TASK>\n deferred_split_folio+0x18c/0x220\n map_anon_folio_pmd_nopf+0xdd/0x130\n map_anon_folio_pmd_pf+0x14/0xb0\n do_huge_pmd_anonymous_page+0x1a1/0x620\n __handle_mm_fault+0xea9/0x10d0\n handle_mm_fault+0xe5/0x320\n do_user_addr_fault+0x1cc/0x870\n exc_page_fault+0x81/0x1b0\n asm_exc_page_fault+0x27/0x30\n </TASK>\n\nHarmless, the WARN_ON_ONCE() is what keeps the out of bounds unit[] read\nfrom happening, but the id should not look valid in the first place. \nClear it before returning.\n\nTwo other spots could paper over this: drop the id in __list_lru_init()\nwhen nokmem turns memcg_aware off, or make deferred_split_folio() pass\nNULL like list_lru_add_obj() does.  Both leave shrinker->id lying around\nfor the next caller, so fix it where the id is handed out.","state":0,"publishedAt":"2026-10-06T08:45:00.458+00:00","modifiedAt":"2026-10-19T09:15:57.057+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"mm/shrinker.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"fafaeceb89a5e2e856ff04c2cacb6cae4a2ecb67\",\n                            \"lessThan\": \"469c12a69ab1842a9090b6c074ffedbfd9584f9c\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"fafaeceb89a5e2e856ff04c2cacb6cae4a2ecb67\",\n                            \"lessThan\": \"932cfb25e7ce98d1f93895671ec186a3087e4f80\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"mm/shrinker.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"7.2\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"7.2\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.8\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/469c12a69ab1842a9090b6c074ffedbfd9584f9c","https://git.kernel.org/stable/c/932cfb25e7ce98d1f93895671ec186a3087e4f80"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98225","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98225","identifiers":["CVE-2026-98225"]},"retained":false,"historicalAffected":[]}],"coverage":[]}