{"id":"CVE-2025-39899","state":"PUBLISHED","title":"mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE\n\nWith CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using\nkmap_local_page(), which requires unmapping in Last-In-First-Out order.\n\nThe current code maps dst_pte first, then src_pte, but unmaps them in the\nsame order (dst_pte, src_pte), violating the LIFO requirement.  This\ncauses the warning in kunmap_local_indexed():\n\n  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c\n  addr \\!= __fix_to_virt(FIX_KMAP_BEGIN + idx)\n\nFix this by reversing the unmap order to respect LIFO ordering.\n\nThis issue follows the same pattern as similar fixes:\n- commit eca6828403b8 (\"crypto: skcipher - fix mismatch between mapping and unmapping order\")\n- commit 8cf57c6df818 (\"nilfs2: eliminate staggered calls to kunmap in nilfs_rename\")\n\nBoth of which addressed the same fundamental requirement that kmap_local\noperations must follow LIFO ordering.","publishedAt":"2025-10-01T07:42:47.100Z","updatedAt":"2026-05-11T21:38:33.572Z","severity":{"score":5.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"b051f707018967ea8f697d790a1ed8c443f63812","versionType":"git"},{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"bd1ee62759d0bd4d6b909731c076c230ac89d61e","versionType":"git"},{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"9614d8bee66387501f48718fa306e17f2aa3f2f3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/userfaultfd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.46","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.6","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/userfaultfd.c"]}],"references":["https://git.kernel.org/stable/c/b051f707018967ea8f697d790a1ed8c443f63812","https://git.kernel.org/stable/c/bd1ee62759d0bd4d6b909731c076c230ac89d61e","https://git.kernel.org/stable/c/9614d8bee66387501f48718fa306e17f2aa3f2f3"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/39xxx/CVE-2025-39899.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39899","state":"PUBLISHED","datePublished":"2025-10-01T07:42:47.100Z","dateUpdated":"2026-05-11T21:38:33.572Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.146Z"},"containers":{"cna":{"title":"mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE\n\nWith CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using\nkmap_local_page(), which requires unmapping in Last-In-First-Out order.\n\nThe current code maps dst_pte first, then src_pte, but unmaps them in the\nsame order (dst_pte, src_pte), violating the LIFO requirement.  This\ncauses the warning in kunmap_local_indexed():\n\n  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c\n  addr \\!= __fix_to_virt(FIX_KMAP_BEGIN + idx)\n\nFix this by reversing the unmap order to respect LIFO ordering.\n\nThis issue follows the same pattern as similar fixes:\n- commit eca6828403b8 (\"crypto: skcipher - fix mismatch between mapping and unmapping order\")\n- commit 8cf57c6df818 (\"nilfs2: eliminate staggered calls to kunmap in nilfs_rename\")\n\nBoth of which addressed the same fundamental requirement that kmap_local\noperations must follow LIFO ordering."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"b051f707018967ea8f697d790a1ed8c443f63812","versionType":"git"},{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"bd1ee62759d0bd4d6b909731c076c230ac89d61e","versionType":"git"},{"version":"adef440691bab824e39c1b17382322d195e1fab0","status":"affected","lessThan":"9614d8bee66387501f48718fa306e17f2aa3f2f3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/userfaultfd.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.46","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.6","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/userfaultfd.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b051f707018967ea8f697d790a1ed8c443f63812"},{"url":"https://git.kernel.org/stable/c/bd1ee62759d0bd4d6b909731c076c230ac89d61e"},{"url":"https://git.kernel.org/stable/c/9614d8bee66387501f48718fa306e17f2aa3f2f3"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:38:33.572Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.12.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.16.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.5,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"id":"CVE-2025-39899","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-01-14T19:29:05.314319Z"}}}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","description":"CWE-noinfo Not enough information"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-01-14T19:33:14.117Z"}}]}}}