CVE-2026-53085

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

bpf: fix mm lifecycle in open-coded task_vma iterator

The open-coded task_vma iterator reads task->mm locklessly and acquires mmap_read_trylock() but never calls mmget(). If the task exits concurrently, the mm_struct can be freed as it is not SLAB_TYPESAFE_BY_RCU, resulting in a use-after-free.

Safely read task->mm with a trylock on alloc_lock and acquire an mm reference. Drop the reference via bpf_iter_mmput_async() in _destroy() and error paths. bpf_iter_mmput_async() is a local wrapper around mmput_async() with a fallback to mmput() on !CONFIG_MMU.

Reject irqs-disabled contexts (including NMI) up front. Operations used by _next() and _destroy() (mmap_read_unlock, bpf_iter_mmput_async) take spinlocks with IRQs disabled (pool->lock, pi_lock). Running from NMI or from a tracepoint that fires with those locks held could deadlock.

A trylock on alloc_lock is used instead of the blocking task_lock() (get_task_mm) to avoid a deadlock when a softirq BPF program iterates a task that already holds its alloc_lock on the same CPU.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/239cec25a22662dbd80f57d94b38178c8be95269
• https://git.kernel.org/stable/c/43683bb280330f3d36f0f2a3932a4867b9603e9c
• https://git.kernel.org/stable/c/d0862de7c866c5bd7c32531f66738c21197af888
• https://git.kernel.org/stable/c/d8e27d2d22b6e2df3a0125b8c08e9aace38c954c
• https://access.redhat.com/security/cve/CVE-2026-53085
• https://bugzilla.redhat.com/show_bug.cgi?id=2492404
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53085.json