Re: [PATCH v2] bpf: Fix use-after-free on mm_struct in bpf_find_vma()

[Sanghyun Park]

Hello Yonghong,

Thank you for the feedback. You are right on both points.

In v3 I will drop get_task_mm()+mmput() and instead mirror the pattern
from upstream commit d8e27d2d22b6 ("bpf: fix mm lifecycle in open-coded
task_vma iterator"): use spin_trylock(&task->alloc_lock) to read task->mm
and mmget() to pin it, then release the reference with mmput_async(). I
will also reject irqs-disabled contexts and !CONFIG_MMU on the foreign
path, and fix the whitespace damage.

v3 coming shortly.

Sincerely,
Sanghyun