Re: [PATCH 5/9] treewide: use kv[mz]alloc* rather than opencoded variants

From: Kees Cook
Date: Mon Jan 30 2017 - 14:24:17 EST

On Mon, Jan 30, 2017 at 1:49 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
> There are many code paths opencoding kvmalloc. Let's use the helper
> instead. The main difference to kvmalloc is that those users are usually
> not considering all the aspects of the memory allocator. E.g. allocation
> requests <= 32kB (with 4kB pages) are basically never failing and invoke
> OOM killer to satisfy the allocation. This sounds too disruptive for
> something that has a reasonable fallback - the vmalloc. On the other
> hand those requests might fallback to vmalloc even when the memory
> allocator would succeed after several more reclaim/compaction attempts
> previously. There is no guarantee something like that happens though.
> This patch converts many of those places to kv[mz]alloc* helpers because
> they are more conservative.
> Changes since v1
> - add kvmalloc_array - this might silently fix some overflow issues
> because most users simply didn't check the overflow for the vmalloc
> fallback.

Awesome, thanks for adding that API. :)

Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>


Kees Cook
Nexus Security