linux-kernel - Re: [PATCH] Fix IB va_start+ib_bytes range check on 32Bit systems

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Message-ID: <26c98d79-025c-bdf6-4bbe-bfd083cb6720@daenzer.net>
Date:   Wed, 29 Mar 2017 23:54:28 +0900
From:   Michel Dänzer <michel@...nzer.net>
To:     Christian König <deathsimple@...afone.de>,
        Jan Burgmeier <jan.burgmeier@...con-software.com>
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, airlied@...ux.ie
Subject: Re: [PATCH] Fix IB va_start+ib_bytes range check on 32Bit systems

On 29/03/17 10:22 PM, Christian König wrote:
> Am 29.03.2017 um 11:18 schrieb Jan Burgmeier:
>> Signed-off-by: Jan Burgmeier <jan.burgmeier@...con-software.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 99424cb8020b..583d22974e14 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -908,6 +908,7 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device
>> *adev,
>>               struct amdgpu_bo *aobj = NULL;
>>               uint64_t offset;
>>               uint8_t *kptr;
>> +            uint64_t it_last;
>>                 m = amdgpu_cs_find_mapping(parser, chunk_ib->va_start,
>>                              &aobj);
>> @@ -916,8 +917,9 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device
>> *adev,
>>                   return -EINVAL;
>>               }
>>   +            it_last = m->it.last;
>>               if ((chunk_ib->va_start + chunk_ib->ib_bytes) >
>> -                (m->it.last + 1) * AMDGPU_GPU_PAGE_SIZE) {
>> +                (it_last + 1) * AMDGPU_GPU_PAGE_SIZE) {
> 
> Nice catch, but just adding a u64 case should do here as well. E.g:
> 
> if ((chunk_ib->va_start + chunk_ib->ib_bytes) >
>     (u64)(m->it.last + 1) * AMDGPU_GPU_PAGE_SIZE) {

That won't work correctly if m->it.last == 0xffffffff ? Or is that not
possible?


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer