{"id":"CVE-2025-21907","title":"mm: memory-failure: update ttu flag inside unmap_poisoned_folio","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: memory-failure: update ttu flag inside unmap_poisoned_folio\n\nPatch series \"mm: memory_failure: unmap poisoned folio during migrate\nproperly\", v3.\n\nFix two bugs duri…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < 608cc7deb428f1122ed426060233622ebf667b6e","Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < 425c12c076e6fc6b2cb04b9f960319d31dcabc76","Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < b81679b1633aa43c0d973adfa816d78c1ed0d032","Linux deab8114fb67dcb0e6293b665c3c7083fbadff17","Linux 6dcf132fe236045bd7f50c008660ea086d09af1f","Linux >= 6.1.16 < 6.2","Linux >= 6.2.3 < 6.3","Linux 6.3"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T20:36:33.206497Z"},"published":"2025-04-01","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:41:47.231Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-21907","references":[{"url":"https://git.kernel.org/stable/c/608cc7deb428f1122ed426060233622ebf667b6e"},{"url":"https://git.kernel.org/stable/c/425c12c076e6fc6b2cb04b9f960319d31dcabc76"},{"url":"https://git.kernel.org/stable/c/b81679b1633aa43c0d973adfa816d78c1ed0d032"}],"tags":["cve.org"],"epss":0.00203,"epssPercentile":0.10346,"ingestedAt":"2026-11-05T22:38:31.853Z","slug":"CVE-2025-21907","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmm: memory-failure: update ttu flag inside unmap_poisoned_folio\n\nPatch series \"mm: memory_failure: unmap poisoned folio during migrate\nproperly\", v3.\n\nFix two bugs during folio migration if the folio is poisoned.\n\n\nThis patch (of 3):\n\nCommit 6da6b1d4a7df (\"mm/hwpoison: convert TTU_IGNORE_HWPOISON to\nTTU_HWPOISON\") introduce TTU_HWPOISON to replace TTU_IGNORE_HWPOISON in\norder to stop send SIGBUS signal when accessing an error page after a\nmemory error on a clean folio.  However during page migration, anon folio\nmust be set with TTU_HWPOISON during unmap_*().  For pagecache we need\nsome policy just like the one in hwpoison_user_mappings to set this flag. \nSo move this policy from hwpoison_user_mappings to unmap_poisoned_folio to\nhandle this warning properly.\n\nWarning will be produced during unamp poison folio with the following log:\n\n  ------------[ cut here ]------------\n  WARNING: CPU: 1 PID: 365 at mm/rmap.c:1847 try_to_unmap_one+0x8fc/0xd3c\n  Modules linked in:\n  CPU: 1 UID: 0 PID: 365 Comm: bash Tainted: G        W          6.13.0-rc1-00018-gacdb4bbda7ab #42\n  Tainted: [W]=WARN\n  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015\n  pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n  pc : try_to_unmap_one+0x8fc/0xd3c\n  lr : try_to_unmap_one+0x3dc/0xd3c\n  Call trace:\n   try_to_unmap_one+0x8fc/0xd3c (P)\n   try_to_unmap_one+0x3dc/0xd3c (L)\n   rmap_walk_anon+0xdc/0x1f8\n   rmap_walk+0x3c/0x58\n   try_to_unmap+0x88/0x90\n   unmap_poisoned_folio+0x30/0xa8\n   do_migrate_range+0x4a0/0x568\n   offline_pages+0x5a4/0x670\n   memory_block_action+0x17c/0x374\n   memory_subsys_offline+0x3c/0x78\n   device_offline+0xa4/0xd0\n   state_store+0x8c/0xf0\n   dev_attr_store+0x18/0x2c\n   sysfs_kf_write+0x44/0x54\n   kernfs_fop_write_iter+0x118/0x1a8\n   vfs_write+0x3a8/0x4bc\n   ksys_write+0x6c/0xf8\n   __arm64_sys_write+0x1c/0x28\n   invoke_syscall+0x44/0x100\n   el0_svc_common.constprop.0+0x40/0xe0\n   do_el0_svc+0x1c/0x28\n   el0_svc+0x30/0xd0\n   el0t_64_sync_handler+0xc8/0xcc\n   el0t_64_sync+0x198/0x19c\n  ---[ end trace 0000000000000000 ]---\n\n[mawupeng1@huawei.com: unmap_poisoned_folio(): remove shadowed local `mapping', per Miaohe]\n\n## Affected\n\n- `Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < 608cc7deb428f1122ed426060233622ebf667b6e`\n- `Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < 425c12c076e6fc6b2cb04b9f960319d31dcabc76`\n- `Linux >= 6da6b1d4a7df8c35770186b53ef65d388398e139 < b81679b1633aa43c0d973adfa816d78c1ed0d032`\n- `Linux deab8114fb67dcb0e6293b665c3c7083fbadff17`\n- `Linux 6dcf132fe236045bd7f50c008660ea086d09af1f`\n- `Linux >= 6.1.16 < 6.2`\n- `Linux >= 6.2.3 < 6.3`\n- `Linux 6.3`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}