Re: [PATCH V3] mm: prevent page_frag_alloc() from corrupting the memory

[Andrew Morton]

On Fri, 15 Jul 2022 14:50:13 +0200 Maurizio Lombardi <mlombard@xxxxxxxxxx> wrote:

> A number of drivers call page_frag_alloc() with a
> fragment's size > PAGE_SIZE.
> In low memory conditions, __page_frag_cache_refill() may fail the order 3
> cache allocation and fall back to order 0;
> In this case, the cache will be smaller than the fragment, causing
> memory corruptions.
> 
> Prevent this from happening by checking if the newly allocated cache
> is large enough for the fragment; if not, the allocation will fail
> and page_frag_alloc() will return NULL.

Can we come up with a Fixes: for this?

Should this fix be backported into -stable kernels?