{"api_version":"1","generated_at":"2026-08-15T15:12:58+00:00","cve":"CVE-2026-74482","urls":{"html":"https://cve.report/CVE-2026-74482","api":"https://cve.report/api/cve/CVE-2026-74482.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74482","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74482"},"summary":{"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":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 13:17:53","updated_at":"2026-08-15 13:17:53"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/e3dd774dbfd0b5bc2dbd0995221751b1234f8205","name":"https://git.kernel.org/stable/c/e3dd774dbfd0b5bc2dbd0995221751b1234f8205","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e923bd21058ea02fd0dcd3549d151d143fd036e5","name":"https://git.kernel.org/stable/c/e923bd21058ea02fd0dcd3549d151d143fd036e5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/10065fb891651d9541e7a5a2db84c1e656ece4f9","name":"https://git.kernel.org/stable/c/10065fb891651d9541e7a5a2db84c1e656ece4f9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d640efe94d86d3be893d4c19220362546a637e90","name":"https://git.kernel.org/stable/c/d640efe94d86d3be893d4c19220362546a637e90","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/be106f7855f03d3128ed0ce70ba74b484a90b473","name":"https://git.kernel.org/stable/c/be106f7855f03d3128ed0ce70ba74b484a90b473","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74482","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74482","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected baa355fd331424526e742d41d9b90d5f9d10f716 be106f7855f03d3128ed0ce70ba74b484a90b473 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected baa355fd331424526e742d41d9b90d5f9d10f716 e3dd774dbfd0b5bc2dbd0995221751b1234f8205 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected baa355fd331424526e742d41d9b90d5f9d10f716 10065fb891651d9541e7a5a2db84c1e656ece4f9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected baa355fd331424526e742d41d9b90d5f9d10f716 d640efe94d86d3be893d4c19220362546a637e90 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected baa355fd331424526e742d41d9b90d5f9d10f716 e923bd21058ea02fd0dcd3549d151d143fd036e5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.8","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.8 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.151 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.103 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.44 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.8 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc6 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["mm/huge_memory.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"be106f7855f03d3128ed0ce70ba74b484a90b473","status":"affected","version":"baa355fd331424526e742d41d9b90d5f9d10f716","versionType":"git"},{"lessThan":"e3dd774dbfd0b5bc2dbd0995221751b1234f8205","status":"affected","version":"baa355fd331424526e742d41d9b90d5f9d10f716","versionType":"git"},{"lessThan":"10065fb891651d9541e7a5a2db84c1e656ece4f9","status":"affected","version":"baa355fd331424526e742d41d9b90d5f9d10f716","versionType":"git"},{"lessThan":"d640efe94d86d3be893d4c19220362546a637e90","status":"affected","version":"baa355fd331424526e742d41d9b90d5f9d10f716","versionType":"git"},{"lessThan":"e923bd21058ea02fd0dcd3549d151d143fd036e5","status":"affected","version":"baa355fd331424526e742d41d9b90d5f9d10f716","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["mm/huge_memory.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.8"},{"lessThan":"4.8","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.151","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.103","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.44","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc6","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.151","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.103","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.44","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.8","versionStartIncluding":"4.8","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc6","versionStartIncluding":"4.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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."}],"providerMetadata":{"dateUpdated":"2026-08-15T12:27:15.083Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/be106f7855f03d3128ed0ce70ba74b484a90b473"},{"url":"https://git.kernel.org/stable/c/e3dd774dbfd0b5bc2dbd0995221751b1234f8205"},{"url":"https://git.kernel.org/stable/c/10065fb891651d9541e7a5a2db84c1e656ece4f9"},{"url":"https://git.kernel.org/stable/c/d640efe94d86d3be893d4c19220362546a637e90"},{"url":"https://git.kernel.org/stable/c/e923bd21058ea02fd0dcd3549d151d143fd036e5"}],"title":"mm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74482","datePublished":"2026-08-15T12:27:15.083Z","dateReserved":"2026-08-15T05:44:03.904Z","dateUpdated":"2026-08-15T12:27:15.083Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 13:17:53","lastModifiedDate":"2026-08-15 13:17:53","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74482","Ordinal":"1","Title":"mm/huge_memory: unlock i_mmap_rwsem before releasing after-split","CVE":"CVE-2026-74482","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74482","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"mm/huge_memory: unlock i_mmap_rwsem before releasing after-split"}]}}}