ptp: vmclock: prevent read-only mappings from becoming writable

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Summary

CVECVE-2026-80724
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 08:16:58 UTC
Updated2026-08-28 08:16:58 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ptp: vmclock: prevent read-only mappings from becoming writable vmclock_miscdev_mmap() rejects writable mappings of the shared vmclock ABI page with -EROFS, but leaves VM_MAYWRITE set. Userspace can map the page read-only and then upgrade it to writable with mprotect(), after which the guest can corrupt the host-written timekeeping data (sequence counter, UTC time, TSC offset) that the vmclock ABI defines as read-only. Clear VM_MAYWRITE on the read-only path so the mapping cannot be upgraded, as i915 does for its read-only objects and as fixed in drm/vc4 (CVE-2026-68445) and drm/panthor (CVE-2024-53071).

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 20503272422693d793b84f88bf23fe4e955d3a33 5b4f2bec7bea6c04084d720d731bedee7caf878d git Not specified
CNA Linux Linux affected 20503272422693d793b84f88bf23fe4e955d3a33 2496e141827102d6af512950057d402a2cfb2bfc git Not specified
CNA Linux Linux affected 20503272422693d793b84f88bf23fe4e955d3a33 2e596e7814ba38cdc129991058b6c254ed37cb11 git Not specified
CNA Linux Linux affected 6.13 Not specified
CNA Linux Linux unaffected 6.13 semver Not specified
CNA Linux Linux unaffected 6.18.47 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.11 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2.1 7.2.* semver Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/5b4f2bec7bea6c04084d720d731bedee7caf878d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2496e141827102d6af512950057d402a2cfb2bfc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2e596e7814ba38cdc129991058b6c254ed37cb11 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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