CVE-2026-90303

/// Technical description

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

ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,

a user fault may trigger show_pte() without any lock.

If another thread in the same process concurrently calls munmap(),

the page table pages may be freed while show_pte() is still traversing

them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table

of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the

contention.

For user faults, additionally restrict that show_pte() is called only

when the addr is a user-space address (addr < TASK_SIZE). This is because

the lock of tsk->mm only protects the virtual memory of user address space,

furthermore, dumping the page tables of a kernel-space address for user

faults is unnecessary and may have security implications.

Ke

/// 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