{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "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(&xas); folio && xas.xa_index <= end;\n                        folio = xas_next(&xas)) {\n                ...\n                if (!folio_try_get(folio))   <-- 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."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "mm/filemap.c"
               ],
               "versions": [
                  {
                     "version": "89c1905d9c14",
                     "lessThan": "570dd14bfecf",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "89c1905d9c14",
                     "lessThan": "c225c4f6056b",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "mm/filemap.c"
               ],
               "versions": [
                  {
                     "version": "6.11",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "6.11",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.11.3",
                     "lessThanOrEqual": "6.11.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.12-rc1",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a"
            },
            {
               "url": "https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691"
            }
         ],
         "title": "mm/filemap: fix filemap_get_folios_contig THP panic",
         "x_generator": {
            "engine": "bippy-c9c4e1df01b2"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2024-49873",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}