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

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Message-Id: <20220808171452.d870753e1494b92ba2142116@linux-foundation.org>
Date:   Mon, 8 Aug 2022 17:14:52 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Maurizio Lombardi <mlombard@...hat.com>
Cc:     alexander.duyck@...il.com, kuba@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        chen45464546@....com
Subject: Re: [PATCH V3] mm: prevent page_frag_alloc() from corrupting the
 memory

On Fri, 15 Jul 2022 14:50:13 +0200 Maurizio Lombardi <mlombard@...hat.com> 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?