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Date:   Mon, 25 Sep 2023 10:50:02 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Andrzej Hajda <andrzej.hajda@intel.com>
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Subject: Re: [PATCH 3/9] drm/i915/selftests: Annotate struct perf_series with
 __counted_by
Message-ID: <202309251043.2D1F7D08@keescook>
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On Mon, Sep 25, 2023 at 12:08:36PM +0200, Andrzej Hajda wrote:
> 
> 
> On 22.09.2023 19:32, Kees Cook wrote:
> > Prepare for the coming implementation by GCC and Clang of the __counted_by
> > attribute. Flexible array members annotated with __counted_by can have
> > their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> > (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> > functions).
> > 
> > As found with Coccinelle[1], add __counted_by for struct perf_series.
> > 
> > [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> > 
> > Cc: Jani Nikula <jani.nikula@linux.intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> > Cc: David Airlie <airlied@gmail.com>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: John Harrison <john.c.harrison@Intel.com>
> > Cc: Andi Shyti <andi.shyti@linux.intel.com>
> > Cc: Matthew Brost <matthew.brost@intel.com>
> > Cc: intel-gfx@lists.freedesktop.org
> > Cc: dri-devel@lists.freedesktop.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> I am surprised this is the only finding in i915, I would expected more.

I'm sure there are more, but it's likely my Coccinelle pattern didn't
catch it. There are many many flexible arrays in drm. :)

$ grep -nRH '\[\];$' drivers/gpu/drm include/uapi/drm | grep -v :extern | wc -l
122

If anyone has some patterns I can add to the Coccinelle script, I can
take another pass at it.

> Anyway:
> 
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Thank you!

-Kees

-- 
Kees Cook