linux-kernel - Re: [PATCH] dma-mapping: Lift address space checks out of debug code

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Message-ID: <201910021659.96269C05@keescook>
Date:   Wed, 2 Oct 2019 17:03:08 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Christoph Hellwig <hch@....de>, Laura Abbott <labbott@...hat.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <swboyd@...omium.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Semmle Security Reports <security-reports@...mle.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dma-mapping: Lift address space checks out of debug code

On Wed, Oct 02, 2019 at 04:58:39PM -0700, Kees Cook wrote:
> In the USB case, it'll actually refuse to do the operation. Should
> dma_map_single() similarly fail? I could push these checks down into
> dma_map_single(), which would be a no-change on behavior for USB and
> gain the checks on all other callers...

Which begs the question: are all callers actually checking the result of
dma_map_single(). Many are paired with dma_mapping_error(), but lots
more aren't...

-- 
Kees Cook