{"id":"CVE-2026-74482","revision":"b30c9bfbda0240f890a04e873870df42","records":[{"revision":"b30c9bfbda0240f890a04e873870df42","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74482","aliases":[],"title":"mm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios\n\n__folio_split() keeps dereferencing the mapping after the split:\nshmem_uncharge(mapping->host) and remap_page() while the folios are still\nfrozen/locked, and i_mmap_unlock_read(mapping) at the very end, after the\nafter-split folios have been unlocked and freed.\n\nNothing holds an inode reference across that.  The split relies on @folio\n-- which the beyond-EOF drop loop never removes, as it starts at\nfolio_next(folio) -- staying locked and in the page cache to hold off\neviction.  But the unlock loop unlocks @folio before i_mmap_unlock_read()\nruns.  If the caller's @lock_at is a tail beyond EOF, as memory_failure()\npasses when splitting a poisoned tail of a shmem THP that reaches past\ni_size during truncation, it too is gone from the page cache; so once\n@folio is unlocked no locked, in-cache folio pins the inode, and a\nconcurrent final iput() can evict and RCU-free it before\ni_mmap_unlock_read() touches i_mmap_rwsem:\n\n  BUG: KASAN: slab-use-after-free in __up_read+0x634/0x790\n   i_mmap_unlock_read include/linux/fs.h:537 [inline]\n   __folio_split+0x732/0x1640 mm/huge_memory.c:4100\n   try_to_split_thp_page+0xab/0x390 mm/memory-failure.c:1675\n   memory_failure+0x1394/0x26e0 mm/memory-failure.c:2470\n\n  Freed by task 4601:\n   shmem_free_in_core_inode+0x54/0xb0 mm/shmem.c:5177\n   evict+0x57f/0xac0 fs/inode.c:870\n\nDo every mapping dereference while @folio still pins the inode: drop\ni_mmap_rwsem right after remap_page(), before the loop that unlocks and\nfrees the after-split folios, and clear @mapping so the exit path does not\nunlock it again.  shmem_uncharge() and remap_page() already run before\nthat point, so after this nothing past the unlock loop touches the inode\nor the mapping.\n\nThis is now a rule the split depends on, alongside keeping @folio frozen\nuntil the page cache is updated: no inode or mapping dereference once the\nafter-split folios start being unlocked.","state":0,"publishedAt":"2026-08-15T12:27:15.083+00:00","modifiedAt":"2026-10-16T19:05:49.129+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/huge_memory.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"bc2f5eabaaf60ec18da70b619a8fba1bfb7dea3a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"f87c08060818ebb19bafed37c38244538da25097\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"6f5c272d71845a669e4c8ee5c72b376e29a0e6e5\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"be106f7855f03d3128ed0ce70ba74b484a90b473\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"e3dd774dbfd0b5bc2dbd0995221751b1234f8205\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"10065fb891651d9541e7a5a2db84c1e656ece4f9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"d640efe94d86d3be893d4c19220362546a637e90\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"baa355fd331424526e742d41d9b90d5f9d10f716\",\n                            \"lessThan\": \"e923bd21058ea02fd0dcd3549d151d143fd036e5\",\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/huge_memory.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.8\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.8\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.265\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.216\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.183\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.151\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.103\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.44\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.8\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 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,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/bc2f5eabaaf60ec18da70b619a8fba1bfb7dea3a","https://git.kernel.org/stable/c/f87c08060818ebb19bafed37c38244538da25097","https://git.kernel.org/stable/c/6f5c272d71845a669e4c8ee5c72b376e29a0e6e5","https://git.kernel.org/stable/c/be106f7855f03d3128ed0ce70ba74b484a90b473","https://git.kernel.org/stable/c/e3dd774dbfd0b5bc2dbd0995221751b1234f8205","https://git.kernel.org/stable/c/10065fb891651d9541e7a5a2db84c1e656ece4f9","https://git.kernel.org/stable/c/d640efe94d86d3be893d4c19220362546a637e90","https://git.kernel.org/stable/c/e923bd21058ea02fd0dcd3549d151d143fd036e5"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74482","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74482","identifiers":["CVE-2026-74482"]},"retained":false,"historicalAffected":[]}],"coverage":[]}