CVE-2026-93137

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

bpf: Fix use-after-free on mm_struct in bpf_find_vma()

bpf_find_vma() reads task->mm and calls mmap_read_trylock(mm) without
holding a reference on the mm. On a foreign task, a concurrent exit_mm()
can free the mm_struct between the lockless read and the trylock,
resulting in a use-after-free. mm_struct is not SLAB_TYPESAFE_BY_RCU.

For the current task, task->mm is stable. For a foreign task, pin the mm
under task->alloc_lock and release it with mmput_async(), mirroring commit
d8e27d2d22b6 ("bpf: fix mm lifecycle in open-coded task_vma iterator").
Use spin_trylock() instead of get_task_mm() so BPF context does not block
on alloc_lock. Reject irqs-disabled contexts and !CONFIG_MMU on the
foreign-task path because dropping the mm reference is not safe there.

Race:

  CPU0 (BPF program)                  CPU1 (exiting task)
  ============================        ==========================
  bpf_find_vma(foreign_task):
    mm = task->mm
                                      exit_mm():
                                        task->mm = NULL
                                        mmput(mm) -> frees mm_struct
    mmap_read_trylock(mm)
        // UAF on mm