CVE-2026-74599

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm/ptdump: always stabilise against page table freeing using init_mm

Previous commits have established the invariant that kernel page table

freeing is performed while an mmap read lock on init_mm is held, which

fixes races between ptdump and kernel page table freeing over init_mm.

However, x86 and arm64 can perform a ptdump over an mm other than init_mm

via ptdump_walk_pgd() and since kernel memory ranges are shared across

non-kernel mm's, this means that the race still exists for these cases.

Fix this by acquiring a nested mmap write lock for init_mm in

ptdump_walk_pgd().

This is safe as we take this after mmap write locking the mm, and nothing

acquires the init_mm lock first before locking an arbitrary mm, so no

deadlock is possible.

Also update walk_page_range_debug() to assert that init_mm is write

locked, add a comment explaining why and remove some redundant code, and

eliminate the unnecessary and confusing

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References