{"cvss":4.7,"datePublished":"2026-04-22T14:16:42.780","dateUpdated":"2026-11-05T22:18:33.400","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page->flags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]","id":"CVE-2026-31466","raw":{"affected":[{"affectedData":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/linux/leafops.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"426ee10711586617da869c8bb798214965337617","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"722cfaf6b31d31123439e67b5deac6b1261a3dea","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"7ddcf4a245c1c5a91fdd9698757e3d95179ffe41","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"b8c49ad888892ad7b77062b9c102b799a3e9b4f8","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"7ad1997b9bc8032603df8f091761114479285769","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"4c5e7f0fcd592801c9cc18f29f80fbee84eb8669","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/linux/leafops.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.5"},{"lessThan":"4.5","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.253","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.203","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.168","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.134","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.81","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.21","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"affectedData":[{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.5","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.7","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.5","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.7","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.5","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.7","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.5","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.7","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.5","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.7","versionType":"custom"}]}],"source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"configurations":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"5817BDB6-4C64-4AB6-83FF-CC693A5E4906","versionEndExcluding":"5.10.253","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"20DDB3E9-AABF-4107-ADB0-5362AA067045","versionEndExcluding":"5.15.203","versionStartIncluding":"5.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B","versionEndExcluding":"6.1.168","versionStartIncluding":"5.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"F56F925B-BAF8-4F4B-B62F-1496AF19A307","versionEndExcluding":"6.6.134","versionStartIncluding":"6.2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC","versionEndExcluding":"6.12.81","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"ED39847A-3B46-4729-B7CA-B2C30B9FA8FE","versionEndExcluding":"6.18.21","versionStartIncluding":"6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","matchCriteriaId":"4CA2E747-A9EC-4518-9AA2-B4247FC748B7","versionEndExcluding":"6.19.11","versionStartIncluding":"6.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*","matchCriteriaId":"F253B622-8837-4245-BCE5-A7BF8FC76A16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*","matchCriteriaId":"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*","matchCriteriaId":"F666C8D8-6538-46D4-B318-87610DE64C34","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*","matchCriteriaId":"02259FDA-961B-47BC-AE7F-93D7EC6E90C2","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*","matchCriteriaId":"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258","vulnerable":true}],"negate":false,"operator":"OR"}]}],"cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page->flags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]"}],"id":"CVE-2026-31466","lastModified":"2026-11-05T22:18:33.400","metrics":{"cvssMetricV31":[{"cvssData":{"attackComplexity":"HIGH","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":4.7,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"exploitabilityScore":1.0,"impactScore":3.6,"source":"nvd@nist.gov","type":"Primary"}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"id":"CVE-2026-31466","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-11-05T21:34:30.187623Z","version":"2.0.3"}}]},"published":"2026-04-22T14:16:42.780","references":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8"},{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"url":"https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd"},{"source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"},{"source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html"},{"source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html"}],"sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","vulnStatus":"Modified","weaknesses":[{"description":[{"lang":"en","value":"CWE-362"}],"source":"nvd@nist.gov","type":"Primary"}]},"severity":"MEDIUM","source":"nvd","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softle..."}