x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-22090
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-04-16 15:16:03 UTC
Updated2026-07-14 13:17:30 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range() If track_pfn_copy() fails, we already added the dst VMA to the maple tree. As fork() fails, we'll cleanup the maple tree, and stumble over the dst VMA for which we neither performed any reservation nor copied any page tables. Consequently untrack_pfn() will see VM_PAT and try obtaining the PAT information from the page table -- which fails because the page table was not copied. The easiest fix would be to simply clear the VM_PAT flag of the dst VMA if track_pfn_copy() fails. However, the whole thing is about "simply" clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy() and performed a reservation, but copying the page tables fails, we'll simply clear the VM_PAT flag, not properly undoing the reservation ... which is also wrong. So let's fix it properly: set the VM_PAT flag only if the reservation succeeded (leaving it clear initially), and undo the reservation if anything goes wrong while copying the page tables: clearing the VM_PAT flag after undoing the reservation. Note that any copied page table entries will get zapped when the VMA will get removed later, after copy_page_range() succeeded; as VM_PAT is not set then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be happy. Note that leaving these page tables in place without a reservation is not a problem, as we are aborting fork(); this process will never run. A reproducer can trigger this usually at the first try: https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110 Modules linked in: ... CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:get_pat_info+0xf6/0x110 ... Call Trace: <TASK> ... untrack_pfn+0x52/0x110 unmap_single_vma+0xa6/0xe0 unmap_vmas+0x105/0x1f0 exit_mmap+0xf6/0x460 __mmput+0x4b/0x120 copy_process+0x1bf6/0x2aa0 kernel_clone+0xab/0x440 __do_sys_clone+0x66/0x90 do_syscall_64+0x95/0x180 Likely this case was missed in: d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed") ... and instead of undoing the reservation we simply cleared the VM_PAT flag. Keep the documentation of these functions in include/linux/pgtable.h, one place is more than sufficient -- we should clean that up for the other functions like track_pfn_remap/untrack_pfn separately.

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

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 2ab640379a0ab4cef746ced1d7e04a0941774bcb a6623712ba8449876f0b3de9462831523fb851e4 git Not specified
CNA Linux Linux affected 2ab640379a0ab4cef746ced1d7e04a0941774bcb b07398e8a5da517083f5c3f2daa8f6681b48ab28 git Not specified
CNA Linux Linux affected 2ab640379a0ab4cef746ced1d7e04a0941774bcb 8d6373f83f367dbed316ddeb178130a3a64b5b67 git Not specified
CNA Linux Linux affected 2ab640379a0ab4cef746ced1d7e04a0941774bcb da381c33f3aa6406406c9fdf07b8b0b63e0ce722 git Not specified
CNA Linux Linux affected 2ab640379a0ab4cef746ced1d7e04a0941774bcb de6185b8892d88142ef69768fe4077cbf40109c0 git Not specified
CNA Linux Linux affected 2ab640379a0ab4cef746ced1d7e04a0941774bcb dc84bc2aba85a1508f04a936f9f9a15f64ebfb31 git Not specified
CNA Linux Linux affected 2.6.29 Not specified
CNA Linux Linux unaffected 2.6.29 semver Not specified
CNA Linux Linux unaffected 6.1.160 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.87 6.6.* 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
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a6623712ba8449876f0b3de9462831523fb851e4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b07398e8a5da517083f5c3f2daa8f6681b48ab28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/8d6373f83f367dbed316ddeb178130a3a64b5b67 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/de6185b8892d88142ef69768fe4077cbf40109c0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/da381c33f3aa6406406c9fdf07b8b0b63e0ce722 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/dc84bc2aba85a1508f04a936f9f9a15f64ebfb31 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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