Description

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.

Metrics

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

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CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

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CVSS 3.x Severity and Vector Strings:

NIST: NVD

Base Score:  5.5 MEDIUM

Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS 2.0 Severity and Vector Strings:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a	Patch
https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691	Patch

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-476	NULL Pointer Dereference	NIST

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Change History

2 change records found show changes

Initial Analysis by NIST 10/24/2024 4:22:42 PM

Action	Type	Old Value	New Value
Added	CVSS V3.1		NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Added	CWE		NIST CWE-476
Added	CPE Configuration		OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.11 up to (excluding) 6.11.3
Changed	Reference Type	https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a No Types Assigned	https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a Patch
Changed	Reference Type	https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691 No Types Assigned	https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691 Patch

New CVE Received from kernel.org 10/21/2024 2:15:08 PM

Action	Type	Old Value	New Value
Added	Description		Record truncated, showing 500 of 1548 characters. View Entire Change Record 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
Added	Reference		kernel.org https://git.kernel.org/stable/c/570dd14bfecf281fa467c80f8ec92b26370ee36a [No types assigned]
Added	Reference		kernel.org https://git.kernel.org/stable/c/c225c4f6056b46a8a5bf2ed35abf17a2d6887691 [No types assigned]