[PATCH] drm/amdgpu: fix NULL pointer dereference when run App with DRI_PRIME=1

[Christian König]

Am 25.05.2018 um 10:23 schrieb Zhang, Jerry (Junwei):
> On 05/25/2018 03:54 PM, Christian König wrote:
>> Am 25.05.2018 um 09:20 schrieb Zhang, Jerry (Junwei):
>>> On 05/25/2018 02:44 PM, Christian König wrote:
>>>> NAK, that probably just fixed the symptom but not the underlying 
>>>> problem.
>>>>
>>>> Somebody is accessing the page array when it should never be accessed.
>>>
>>> If prime import as GTT bo by default(now it's CPU bo), it would happens
>>> quickly when GTT sg bo creation rather than next cs validation.
>>>
>>> Since ttm_sg_tt_init() only allocates gtt->ttm.dma_address if sg bo is
>>> created, it would fail to access ttm->pages when ttm populate.
>>
>> And exactly that's the problem, and imported BO should never populate.
>>
>>>
>>> current error happens in ttm populate from cs validation, the sg bo is
>>> imported from exporter.
>>>
>>>>
>>>> How did you manage to trigger this?
>>>
>>> PRI_PRIME=1 with Unigine heaven.
>>
>> Going to give that a try, but the last time I check that worked as 
>> expected.
>
> FYI.
> PRI_PRIME=1 glxinfo will not trigger that, but the game does.

Just tested and it works perfectly fine.

Is that on the closed stack or the open stack?

Christian.

>
> Jerry
>
>>
>> Thanks,
>> Christian.
>>
>>>
>>> Regards,
>>> Jerry
>>>
>>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>> Am 25.05.2018 um 07:41 schrieb Junwei Zhang:
>>>>> [  632.679861] BUG: unable to handle kernel NULL pointer 
>>>>> dereference at (null)
>>>>> [  632.679892] IP: drm_prime_sg_to_page_addr_arrays+0x52/0xb0 [drm]
>>>>> <snip>
>>>>> [  632.680011] Call Trace:
>>>>> [  632.680082]  amdgpu_ttm_tt_populate+0x3e/0xa0 [amdgpu]
>>>>> [  632.680092]  ttm_tt_populate.part.7+0x22/0x60 [amdttm]
>>>>> [  632.680098]  amdttm_tt_bind+0x52/0x60 [amdttm]
>>>>> [  632.680106]  ttm_bo_handle_move_mem+0x54b/0x5c0 [amdttm]
>>>>> [  632.680112]  ? find_next_bit+0xb/0x10
>>>>> [  632.680119]  amdttm_bo_validate+0x11d/0x130 [amdttm]
>>>>> [  632.680176]  amdgpu_cs_bo_validate+0x9d/0x150 [amdgpu]
>>>>> [  632.680232]  amdgpu_cs_validate+0x41/0x270 [amdgpu]
>>>>> [  632.680288]  amdgpu_cs_list_validate+0xc7/0x1a0 [amdgpu]
>>>>> [  632.680343]  amdgpu_cs_ioctl+0x1634/0x1c00 [amdgpu]
>>>>> [  632.680401]  ? amdgpu_cs_find_mapping+0x120/0x120 [amdgpu]
>>>>> [  632.680416]  drm_ioctl_kernel+0x6b/0xb0 [drm]
>>>>> [  632.680431]  drm_ioctl+0x3e4/0x450 [drm]
>>>>> [  632.680485]  ? amdgpu_cs_find_mapping+0x120/0x120 [amdgpu]
>>>>> [  632.680537]  amdgpu_drm_ioctl+0x4c/0x80 [amdgpu]
>>>>> [  632.680542]  do_vfs_ioctl+0xa4/0x600
>>>>> [  632.680546]  ? SyS_futex+0x7f/0x180
>>>>> [  632.680549]  SyS_ioctl+0x79/0x90
>>>>> [  632.680554]  entry_SYSCALL_64_fastpath+0x24/0xab
>>>>>
>>>>> Signed-off-by: Junwei Zhang <Jerry.Zhang at amd.com>
>>>>> ---
>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
>>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>> index 57d4da6..b293809 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>>>> @@ -1212,7 +1212,7 @@ static struct ttm_tt 
>>>>> *amdgpu_ttm_tt_create(struct
>>>>> ttm_buffer_object *bo,
>>>>>       gtt->ttm.ttm.func = &amdgpu_backend_func;
>>>>>       /* allocate space for the uninitialized page entries */
>>>>> -    if (ttm_sg_tt_init(&gtt->ttm, bo, page_flags)) {
>>>>> +    if (ttm_dma_tt_init(&gtt->ttm, bo, page_flags)) {
>>>>>           kfree(gtt);
>>>>>           return NULL;
>>>>>       }
>>>>
>>