cve-2024-49873
Vulnerability from cvelistv5
Published
2024-10-21 18:01
Modified
2024-12-19 09:28
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/filemap: fix filemap_get_folios_contig THP panic Patch series "memfd-pin huge page fixes". Fix multiple bugs that occur when using memfd_pin_folios with hugetlb pages and THP. The hugetlb bugs only bite when the page is not yet faulted in when memfd_pin_folios is called. The THP bug bites when the starting offset passed to memfd_pin_folios is not huge page aligned. See the commit messages for details. This patch (of 5): memfd_pin_folios on memory backed by THP panics if the requested start offset is not huge page aligned: BUG: kernel NULL pointer dereference, address: 0000000000000036 RIP: 0010:filemap_get_folios_contig+0xdf/0x290 RSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202 RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002 The fault occurs here, because xas_load returns a folio with value 2: filemap_get_folios_contig() for (folio = xas_load(&xas); folio && xas.xa_index <= end; folio = xas_next(&xas)) { ... if (!folio_try_get(folio)) <-- BOOM "2" is an xarray sibling entry. We get it because memfd_pin_folios does not round the indices passed to filemap_get_folios_contig to huge page boundaries for THP, so we load from the middle of a huge page range see a sibling. (It does round for hugetlbfs, at the is_file_hugepages test). To fix, if the folio is a sibling, then return the next index as the starting point for the next call to filemap_get_folios_contig.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691Patch
Impacted products
Vendor Product Version
Linux Linux Version: 89c1905d9c140372b7f50ef48f42378cf85d9bc5
Version: 89c1905d9c140372b7f50ef48f42378cf85d9bc5
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   Linux Linux Version: 6.11
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                "timestamp": "2024-10-22T13:46:41.000217Z",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/filemap: fix filemap_get_folios_contig THP panic\n\nPatch series \"memfd-pin huge page fixes\".\n\nFix multiple bugs that occur when using memfd_pin_folios with hugetlb\npages and THP.  The hugetlb bugs only bite when the page is not yet\nfaulted in when memfd_pin_folios is called.  The THP bug bites when the\nstarting offset passed to memfd_pin_folios is not huge page aligned.  See\nthe commit messages for details.\n\n\nThis patch (of 5):\n\nmemfd_pin_folios on memory backed by THP panics if the requested start\noffset is not huge page aligned:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000036\nRIP: 0010:filemap_get_folios_contig+0xdf/0x290\nRSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202\nRAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002\n\nThe fault occurs here, because xas_load returns a folio with value 2:\n\n    filemap_get_folios_contig()\n        for (folio = xas_load(\u0026xas); folio \u0026\u0026 xas.xa_index \u003c= end;\n                        folio = xas_next(\u0026xas)) {\n                ...\n                if (!folio_try_get(folio))   \u003c-- BOOM\n\n\"2\" is an xarray sibling entry.  We get it because memfd_pin_folios does\nnot round the indices passed to filemap_get_folios_contig to huge page\nboundaries for THP, so we load from the middle of a huge page range see a\nsibling.  (It does round for hugetlbfs, at the is_file_hugepages test).\n\nTo fix, if the folio is a sibling, then return the next index as the\nstarting point for the next call to filemap_get_folios_contig."
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See\\nthe commit messages for details.\\n\\n\\nThis patch (of 5):\\n\\nmemfd_pin_folios on memory backed by THP panics if the requested start\\noffset is not huge page aligned:\\n\\nBUG: kernel NULL pointer dereference, address: 0000000000000036\\nRIP: 0010:filemap_get_folios_contig+0xdf/0x290\\nRSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202\\nRAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002\\n\\nThe fault occurs here, because xas_load returns a folio with value 2:\\n\\n    filemap_get_folios_contig()\\n        for (folio = xas_load(\u0026xas); folio \u0026\u0026 xas.xa_index \u003c= end;\\n                        folio = xas_next(\u0026xas)) {\\n                ...\\n                if (!folio_try_get(folio))   \u003c-- BOOM\\n\\n\\\"2\\\" is an xarray sibling entry.  We get it because memfd_pin_folios does\\nnot round the indices passed to filemap_get_folios_contig to huge page\\nboundaries for THP, so we load from the middle of a huge page range see a\\nsibling.  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(S\u00ed redondea para hugetlbfs, en la prueba is_file_hugepages). Para solucionarlo, si el folio es un hermano, entonces devuelva el siguiente \u00edndice como punto de inicio para la siguiente llamada a filemap_get_folios_contig.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-476\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.11\",\"versionEndExcluding\":\"6.11.3\",\"matchCriteriaId\":\"54D9C704-D679-41A7-9C40-10A6B1E7FFE9\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
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