[PATCH 1/2] drm/radeon: forbid mapping of userptr bo through radeon device file

[PATCH 1/2] drm/radeon: forbid mapping of userptr bo through radeon device file

[Jérôme Glisse]

Allowing userptr bo which are basicly a list of page from some vma
(so either anonymous page or file backed page) would lead to serious
corruption of kernel structures and counters (because we overwrite
the page->mapping field when mapping buffer).

This will already block if the buffer was populated before anyone does
try to mmap it because then TTM_PAGE_FLAG_SG would be set in in the
ttm_tt flags. But that flag is check before ttm_tt_populate in the ttm
vm fault handler.

So to be safe just add a check to verify_access() callback.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: <stable@vger.kernel.org>
---
 drivers/gpu/drm/radeon/radeon_ttm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 7dddfdc..90f7394 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -235,6 +235,8 @@ static int radeon_verify_access(struct ttm_buffer_object *bo, struct file *filp)
 {
 	struct radeon_bo *rbo = container_of(bo, struct radeon_bo, tbo);
 
+	if (radeon_ttm_tt_has_userptr(bo->ttm))
+		return -EPERM;
 	return drm_vma_node_verify_access(&rbo->gem_base.vma_node, filp);
 }
 
-- 
2.1.0

[PATCH 2/2] drm/amdgpu: forbid mapping of userptr bo through radeon device file

[Jérôme Glisse]

Allowing userptr bo which are basicly a list of page from some vma
(so either anonymous page or file backed page) would lead to serious
corruption of kernel structures and counters (because we overwrite
the page->mapping field when mapping buffer).

This will already block if the buffer was populated before anyone does
try to mmap it because then TTM_PAGE_FLAG_SG would be set in in the
ttm_tt flags. But that flag is check before ttm_tt_populate in the ttm
vm fault handler.

So to be safe just add a check to verify_access() callback.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: <stable@vger.kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 6f3369d..11af449 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -223,6 +223,8 @@ static int amdgpu_verify_access(struct ttm_buffer_object *bo, struct file *filp)
 {
 	struct amdgpu_bo *rbo = container_of(bo, struct amdgpu_bo, tbo);
 
+	if (amdgpu_ttm_tt_get_usermm(bo->ttm))
+		return -EPERM;
 	return drm_vma_node_verify_access(&rbo->gem_base.vma_node, filp);
 }
 
-- 
2.1.0

Re: [PATCH 1/2] drm/radeon: forbid mapping of userptr bo through radeon device file

[Christian König]

There are also checks in (amdgpu|radeon)_gem_mmap_ioctl() to prevent 
this as well.

But it shouldn't hurt us to check that here as well. So both patches are 
Reviewed-by: Christian König <christian.koenig@amd.com>

Regards,
Christian.

Am 19.04.2016 um 15:07 schrieb Jérôme Glisse:
> Allowing userptr bo which are basicly a list of page from some vma
> (so either anonymous page or file backed page) would lead to serious
> corruption of kernel structures and counters (because we overwrite
> the page->mapping field when mapping buffer).
>
> This will already block if the buffer was populated before anyone does
> try to mmap it because then TTM_PAGE_FLAG_SG would be set in in the
> ttm_tt flags. But that flag is check before ttm_tt_populate in the ttm
> vm fault handler.
>
> So to be safe just add a check to verify_access() callback.
>
> Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
> Cc: <stable@vger.kernel.org>
> ---
>   drivers/gpu/drm/radeon/radeon_ttm.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 7dddfdc..90f7394 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -235,6 +235,8 @@ static int radeon_verify_access(struct ttm_buffer_object *bo, struct file *filp)
>   {
>   	struct radeon_bo *rbo = container_of(bo, struct radeon_bo, tbo);
>   
> +	if (radeon_ttm_tt_has_userptr(bo->ttm))
> +		return -EPERM;
>   	return drm_vma_node_verify_access(&rbo->gem_base.vma_node, filp);
>   }
>   

Re: [PATCH 1/2] drm/radeon: forbid mapping of userptr bo through radeon device file

[Alex Deucher]

On Wed, Apr 20, 2016 at 9:26 AM, Christian König
<deathsimple@vodafone.de> wrote:
> There are also checks in (amdgpu|radeon)_gem_mmap_ioctl() to prevent this as
> well.
>
> But it shouldn't hurt us to check that here as well. So both patches are
> Reviewed-by: Christian König <christian.koenig@amd.com>

Applied both.  Thanks!

Alex

>
> Regards,
> Christian.
>
> Am 19.04.2016 um 15:07 schrieb Jérôme Glisse:
>>
>> Allowing userptr bo which are basicly a list of page from some vma
>> (so either anonymous page or file backed page) would lead to serious
>> corruption of kernel structures and counters (because we overwrite
>> the page->mapping field when mapping buffer).
>>
>> This will already block if the buffer was populated before anyone does
>> try to mmap it because then TTM_PAGE_FLAG_SG would be set in in the
>> ttm_tt flags. But that flag is check before ttm_tt_populate in the ttm
>> vm fault handler.
>>
>> So to be safe just add a check to verify_access() callback.
>>
>> Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
>> Cc: <stable@vger.kernel.org>
>> ---
>>   drivers/gpu/drm/radeon/radeon_ttm.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
>> b/drivers/gpu/drm/radeon/radeon_ttm.c
>> index 7dddfdc..90f7394 100644
>> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
>> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
>> @@ -235,6 +235,8 @@ static int radeon_verify_access(struct
>> ttm_buffer_object *bo, struct file *filp)
>>   {
>>         struct radeon_bo *rbo = container_of(bo, struct radeon_bo, tbo);
>>   +     if (radeon_ttm_tt_has_userptr(bo->ttm))
>> +               return -EPERM;
>>         return drm_vma_node_verify_access(&rbo->gem_base.vma_node, filp);
>>   }
>>
>
>
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