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Date:   Thu, 15 Apr 2021 07:47:22 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Kees Cook <keescook@chromium.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>, x86@kernel.org,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH 1/2] x86/events/amd/iommu: Fix sysfs type mismatch
Message-ID: <YHhR+l5Kmdy6OSSL@archlinux-ax161>
References: <20210415001112.3024673-1-nathan@kernel.org>
 <20210415075335.GA1954964@infradead.org>
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On Thu, Apr 15, 2021 at 08:53:35AM +0100, Christoph Hellwig wrote:
> On Wed, Apr 14, 2021 at 05:11:11PM -0700, Nathan Chancellor wrote:
> > dev_attr_show() calls _iommu_event_show() via an indirect call but
> > _iommu_event_show()'s type does not currently match the type of the
> > show() member in 'struct device_attribute', resulting in a Control Flow
> > Integrity violation.
> 
> While the fix looks fine I think we need to solve this kind of problem
> by better type checking.  The fact that we can use the wong type here
> without a compiler warning is the real issue.

I agree. Unfortunately, it seems that is going to be a much longer tail
project because of how pervasive this is (using container_of() +
attributes to get callbacks).

https://lore.kernel.org/r/202006112217.2E6CE093@keescook/
https://lore.kernel.org/r/202104021823.64FA6119@keescook/

Cheers,
Nathan