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* [PATCH] drm/amdgpu: fix possible null-pointer dereference in amdgpu_ttm_tt_populate()
@ 2021-07-31  8:04 Tuo Li
  2021-08-01 17:19 ` Christian König
  0 siblings, 1 reply; 3+ messages in thread
From: Tuo Li @ 2021-07-31  8:04 UTC (permalink / raw)
  To: alexander.deucher, christian.koenig, Xinhui.Pan, airlied, daniel,
	sumit.semwal, airlied, Felix.Kuehling, Oak.Zeng, nirmoy.das,
	tzimmermann, Philip.Yang
  Cc: amd-gfx, dri-devel, linux-kernel, linux-media, linaro-mm-sig,
	baijiaju1990, Tuo Li, TOTE Robot

The variable ttm is assigned to the variable gtt, and the variable gtt
is checked in:
  if (gtt && gtt->userptr)

This indicates that both ttm and gtt can be NULL.
If so, a null-pointer dereference will occur:
  if (ttm->page_flags & TTM_PAGE_FLAG_SG)

Also, some null-pointer dereferences will occur in the function
ttm_pool_alloc() which is called in:
  return ttm_pool_alloc(&adev->mman.bdev.pool, ttm, ctx);

To fix these possible null-pointer dereferences, the function returns
-EINVAL when ttm is NULL.

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 3a55f08e00e1..80440f799c09 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1120,8 +1120,11 @@ static int amdgpu_ttm_tt_populate(struct ttm_device *bdev,
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
 
+	if (ttm == NULL)
+		return -EINVAL;
+
 	/* user pages are bound by amdgpu_ttm_tt_pin_userptr() */
-	if (gtt && gtt->userptr) {
+	if (gtt->userptr) {
 		ttm->sg = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
 		if (!ttm->sg)
 			return -ENOMEM;
-- 
2.25.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] drm/amdgpu: fix possible null-pointer dereference in amdgpu_ttm_tt_populate()
  2021-07-31  8:04 [PATCH] drm/amdgpu: fix possible null-pointer dereference in amdgpu_ttm_tt_populate() Tuo Li
@ 2021-08-01 17:19 ` Christian König
  2021-08-02  2:47   ` Li Tuo
  0 siblings, 1 reply; 3+ messages in thread
From: Christian König @ 2021-08-01 17:19 UTC (permalink / raw)
  To: Tuo Li, alexander.deucher, Xinhui.Pan, airlied, daniel,
	sumit.semwal, airlied, Felix.Kuehling, Oak.Zeng, nirmoy.das,
	tzimmermann, Philip.Yang
  Cc: amd-gfx, dri-devel, linux-kernel, linux-media, linaro-mm-sig,
	baijiaju1990, TOTE Robot

Am 31.07.21 um 10:04 schrieb Tuo Li:
> The variable ttm is assigned to the variable gtt, and the variable gtt
> is checked in:
>    if (gtt && gtt->userptr)
>
> This indicates that both ttm and gtt can be NULL.
> If so, a null-pointer dereference will occur:
>    if (ttm->page_flags & TTM_PAGE_FLAG_SG)
>
> Also, some null-pointer dereferences will occur in the function
> ttm_pool_alloc() which is called in:
>    return ttm_pool_alloc(&adev->mman.bdev.pool, ttm, ctx);
>
> To fix these possible null-pointer dereferences, the function returns
> -EINVAL when ttm is NULL.

NAK, the NULL test is just a leftover from when the objects where distinct.

Please remove the NULL test instead.

Regards,
Christian.

>
> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@gmail.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 3a55f08e00e1..80440f799c09 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1120,8 +1120,11 @@ static int amdgpu_ttm_tt_populate(struct ttm_device *bdev,
>   	struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
>   	struct amdgpu_ttm_tt *gtt = (void *)ttm;
>   
> +	if (ttm == NULL)
> +		return -EINVAL;
> +
>   	/* user pages are bound by amdgpu_ttm_tt_pin_userptr() */
> -	if (gtt && gtt->userptr) {
> +	if (gtt->userptr) {
>   		ttm->sg = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
>   		if (!ttm->sg)
>   			return -ENOMEM;


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] drm/amdgpu: fix possible null-pointer dereference in amdgpu_ttm_tt_populate()
  2021-08-01 17:19 ` Christian König
@ 2021-08-02  2:47   ` Li Tuo
  0 siblings, 0 replies; 3+ messages in thread
From: Li Tuo @ 2021-08-02  2:47 UTC (permalink / raw)
  To: Christian König
  Cc: amd-gfx, dri-devel, linux-kernel, airlied, linux-media,
	linaro-mm-sig, Xinhui.Pan, baijiaju1990, alexander.deucher,
	Philip.Yang, TOTE Robot, sumit.semwal, daniel, Felix.Kuehling,
	airlied, Oak.Zeng, nirmoy.das, tzimmermann

Thanks for your feedback! We will remove the null tests according to 
your advice and prepare a V2 patch.

Best wishes,
Tuo Li

On 2021/8/2 1:19, Christian König wrote:
> Am 31.07.21 um 10:04 schrieb Tuo Li:
>> The variable ttm is assigned to the variable gtt, and the variable gtt
>> is checked in:
>>    if (gtt && gtt->userptr)
>>
>> This indicates that both ttm and gtt can be NULL.
>> If so, a null-pointer dereference will occur:
>>    if (ttm->page_flags & TTM_PAGE_FLAG_SG)
>>
>> Also, some null-pointer dereferences will occur in the function
>> ttm_pool_alloc() which is called in:
>>    return ttm_pool_alloc(&adev->mman.bdev.pool, ttm, ctx);
>>
>> To fix these possible null-pointer dereferences, the function returns
>> -EINVAL when ttm is NULL.
>
> NAK, the NULL test is just a leftover from when the objects where 
> distinct.
>
> Please remove the NULL test instead.
>
> Regards,
> Christian.
>
>>
>> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
>> Signed-off-by: Tuo Li <islituo@gmail.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 3a55f08e00e1..80440f799c09 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -1120,8 +1120,11 @@ static int amdgpu_ttm_tt_populate(struct 
>> ttm_device *bdev,
>>       struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
>>       struct amdgpu_ttm_tt *gtt = (void *)ttm;
>>   +    if (ttm == NULL)
>> +        return -EINVAL;
>> +
>>       /* user pages are bound by amdgpu_ttm_tt_pin_userptr() */
>> -    if (gtt && gtt->userptr) {
>> +    if (gtt->userptr) {
>>           ttm->sg = kzalloc(sizeof(struct sg_table), GFP_KERNEL);
>>           if (!ttm->sg)
>>               return -ENOMEM;
>


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-08-02  2:47 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-07-31  8:04 [PATCH] drm/amdgpu: fix possible null-pointer dereference in amdgpu_ttm_tt_populate() Tuo Li
2021-08-01 17:19 ` Christian König
2021-08-02  2:47   ` Li Tuo

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