ghsa-j2cc-c4fg-77cq
Vulnerability from github
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.
{
"affected": [],
"aliases": [
"CVE-2024-49873"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-21T18:15:08Z",
"severity": "MODERATE"
},
"details": "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.",
"id": "GHSA-j2cc-c4fg-77cq",
"modified": "2024-10-24T21:31:01Z",
"published": "2024-10-21T18:30:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-49873"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
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