Re: [Intel-gfx] [PATCH] drm/i915: Validate execbuffer start/length arguments against the target bo

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 20 Nov 2015, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Fri, Nov 20, 2015 at 03:11:04PM +0000, Chris Wilson wrote:
>> The offset within and the length of the command sequence to execute are
>> supplied by the user with respect to the batch buffer. We should be
>> validating that region is wholly contained within the batch buffer;
>> make it so.
>> 
>> Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: stable@vger.kernel.org
>> ---
>>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>> index a4c243cec4aa..e38284c1b89f 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
>> @@ -1462,6 +1462,13 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>>  	/* take note of the batch buffer before we might reorder the lists */
>>  	batch_obj = eb_get_batch(eb);
>>  
>> +	if (args->batch_len > batch_obj->base.size ||
>> +	    args->batch_start_offset > batch_obj->base.size - args->batch_len) {
>
> lgtm. No possibility of overflow doing it that way.
>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
>> +		DRM_DEBUG("Attempting to execute commands from beyond the bounds of the batch object\n");
>> +		ret = -EINVAL;
>> +		goto err;
>> +	}
>> +
>>  	/* Move the objects en-masse into the GTT, evicting if necessary. */
>>  	need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
>>  	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, ctx, &need_relocs);
>> -- 
>> 2.6.2
>> 
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-- 
Jani Nikula, Intel Open Source Technology Center