Re: [PATCH v2] mmap: Fix do_brk_flags() modifying obviously incorrect VMAs

[Andrew Morton]

On Mon, 5 Dec 2022 19:23:17 +0000 Liam Howlett <liam.howlett@xxxxxxxxxx> wrote:

> Add more sanity checks to the VMA that do_brk_flags() will expand.
> Ensure the VMA matches basic merge requirements within the function
> before calling can_vma_merge_after().

I't unclear what's actually being fixed here.

Why do you feel we need the above changes?

> Drop the duplicate checks from vm_brk_flags() since they will be
> enforced later.
> 
> Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")

Fixes in what way?  Removing the duplicate checks?