mm/gup: reject FOLL_SPLIT_PMD with hugetlb VMAs

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-22034
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-04-16 15:15:56 UTC
Updated2026-07-30 06:22:04 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/gup: reject FOLL_SPLIT_PMD with hugetlb VMAs Patch series "mm: fixes for device-exclusive entries (hmm)", v2. Discussing the PageTail() call in make_device_exclusive_range() with Willy, I recently discovered [1] that device-exclusive handling does not properly work with THP, making the hmm-tests selftests fail if THPs are enabled on the system. Looking into more details, I found that hugetlb is not properly fenced, and I realized that something that was bugging me for longer -- how device-exclusive entries interact with mapcounts -- completely breaks migration/swapout/split/hwpoison handling of these folios while they have device-exclusive PTEs. The program below can be used to allocate 1 GiB worth of pages and making them device-exclusive on a kernel with CONFIG_TEST_HMM. Once they are device-exclusive, these folios cannot get swapped out (proc$pid/smaps_rollup will always indicate 1 GiB RSS no matter how much one forces memory reclaim), and when having a memory block onlined to ZONE_MOVABLE, trying to offline it will loop forever and complain about failed migration of a page that should be movable. # echo offline > /sys/devices/system/memory/memory136/state # echo online_movable > /sys/devices/system/memory/memory136/state # ./hmm-swap & ... wait until everything is device-exclusive # echo offline > /sys/devices/system/memory/memory136/state [ 285.193431][T14882] page: refcount:2 mapcount:0 mapping:0000000000000000 index:0x7f20671f7 pfn:0x442b6a [ 285.196618][T14882] memcg:ffff888179298000 [ 285.198085][T14882] anon flags: 0x5fff0000002091c(referenced|uptodate| dirty|active|owner_2|swapbacked|node=1|zone=3|lastcpupid=0x7ff) [ 285.201734][T14882] raw: ... [ 285.204464][T14882] raw: ... [ 285.207196][T14882] page dumped because: migration failure [ 285.209072][T14882] page_owner tracks the page as allocated [ 285.210915][T14882] page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), id 14926, tgid 14926 (hmm-swap), ts 254506295376, free_ts 227402023774 [ 285.216765][T14882] post_alloc_hook+0x197/0x1b0 [ 285.218874][T14882] get_page_from_freelist+0x76e/0x3280 [ 285.220864][T14882] __alloc_frozen_pages_noprof+0x38e/0x2740 [ 285.223302][T14882] alloc_pages_mpol+0x1fc/0x540 [ 285.225130][T14882] folio_alloc_mpol_noprof+0x36/0x340 [ 285.227222][T14882] vma_alloc_folio_noprof+0xee/0x1a0 [ 285.229074][T14882] __handle_mm_fault+0x2b38/0x56a0 [ 285.230822][T14882] handle_mm_fault+0x368/0x9f0 ... This series fixes all issues I found so far. There is no easy way to fix without a bigger rework/cleanup. I have a bunch of cleanups on top (some previous sent, some the result of the discussion in v1) that I will send out separately once this landed and I get to it. I wish we could just use some special present PROT_NONE PTEs instead of these (non-present, non-none) fake-swap entries; but that just results in the same problem we keep having (lack of spare PTE bits), and staring at other similar fake-swap entries, that ship has sailed. With this series, make_device_exclusive() doesn't actually belong into mm/rmap.c anymore, but I'll leave moving that for another day. I only tested this series with the hmm-tests selftests due to lack of HW, so I'd appreciate some testing, especially if the interaction between two GPUs wanting a device-exclusive entry works as expected. <program> #include <stdio.h> #include <fcntl.h> #include <stdint.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/ioctl.h> #include <linux/types.h> #include <linux/ioctl.h> #define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd) struct hmm_dmirror_cmd { __u64 addr; __u64 ptr; __u64 npages; __u64 cpages; __u64 faults; }; const size_t size = 1 * 1024 * 1024 * 1024ul; const size_t chunk_size = 2 * 1024 * 1024ul; int m ---truncated---

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

Problem Types: NVD-CWE-noinfo

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 9cb28da54643ad464c47585cd5866c30b0218e67 2e877ff3492267def06dd50cb165dc9ab8838e7d git Not specified
CNA Linux Linux affected 9cb28da54643ad464c47585cd5866c30b0218e67 48d28417c66cce2f3b0ba773fcb6695a56eff220 git Not specified
CNA Linux Linux affected 9cb28da54643ad464c47585cd5866c30b0218e67 fd900832e8440046627b60697687ab5d04398008 git Not specified
CNA Linux Linux affected 9cb28da54643ad464c47585cd5866c30b0218e67 8977752c8056a6a094a279004a49722da15bace3 git Not specified
CNA Linux Linux affected 6.10 Not specified
CNA Linux Linux unaffected 6.10 semver Not specified
CNA Linux Linux unaffected 6.12.23 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.11 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14.2 6.14.* semver Not specified
CNA Linux Linux unaffected 6.15 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/fd900832e8440046627b60697687ab5d04398008 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/48d28417c66cce2f3b0ba773fcb6695a56eff220 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2e877ff3492267def06dd50cb165dc9ab8838e7d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/8977752c8056a6a094a279004a49722da15bace3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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