Overview
About vulnerability
In 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).
Details
- Affected product:
- Debian 10 ELS
- Affected packages:
- linux @ 4.19.0