[Mesa-dev] [PATCH 4/4] i965: Use safer pointer arithmetic in gather_oa_results()

[Kenneth Graunke]

On Tuesday, November 18, 2014 09:11:26 PM Chad Versace wrote:
> This patch reduces the likelihood of pointer arithmetic overflow bugs in
> gather_oa_results(), like the one fixed by b69c7c5dac.
> 
> I haven't yet encountered any overflow bugs in the wild along this
> patch's codepath. But I get nervous when I see code patterns like this:
> 
>    (void*) + (int) * (int)
> 
> I smell 32-bit overflow all over this code.
> 
> This patch retypes 'snapshot_size' to 'ptrdiff_t', which should fix any
> potential overflow.
> 
> Cc: Ian Romanick <idr at freedesktop.org>
> Cc: Kenneth Graunke <kenneth at whitecape.org>
> Signed-off-by: Chad Versace <chad.versace at linux.intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_performance_monitor.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_performance_monitor.c b/src/mesa/drivers/dri/i965/brw_performance_monitor.c
> index edfa3d2..e683e40 100644
> --- a/src/mesa/drivers/dri/i965/brw_performance_monitor.c
> +++ b/src/mesa/drivers/dri/i965/brw_performance_monitor.c
> @@ -907,7 +907,7 @@ gather_oa_results(struct brw_context *brw,
>        return;
>     }
>  
> -   const int snapshot_size = brw->perfmon.entries_per_oa_snapshot;
> +   const ptrdiff_t snapshot_size = brw->perfmon.entries_per_oa_snapshot;
>  
>     /* First, add the contributions from the "head" interval:
>      * (snapshot taken at BeginPerfMonitor time,

And one month later... (sad trombones) :(

Series is:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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