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

[Ian Romanick]

On 12/18/2014 10:14 PM, Kenneth Graunke wrote:
> 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>

I suspect that these should be tagged for 10.4? :(


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