[PATCH] accel/amdxdna: Fix use-after-free in amdxdna_gem_dmabuf_mmap()

[PATCH] accel/amdxdna: Fix use-after-free in amdxdna_gem_dmabuf_mmap()

[Wentao Liang]

When vm_insert_pages() fails, the error path calls vma->vm_ops->close(vma)
which internally calls drm_gem_vm_close() → drm_gem_object_put(), 
releasing the GEM object reference acquired at the start of the function.
However, the close_vma label then falls through to put_obj, which calls
drm_gem_object_put() a second time on the same object.

If the first put releases the last reference, the object is freed and the
second put accesses freed memory, causing a use-after-free.

Fix by returning directly from close_vma instead of falling through to
put_obj, since the close handler already performs all necessary cleanup
including the object put.

Cc: stable@vger.kernel.org
Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/accel/amdxdna/amdxdna_gem.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
index 6e367ddb9e1b..fec9763c518c 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.c
+++ b/drivers/accel/amdxdna/amdxdna_gem.c
@@ -469,6 +469,7 @@ static int amdxdna_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struc
 
 close_vma:
 	vma->vm_ops->close(vma);
+	return ret;
 put_obj:
 	drm_gem_object_put(gobj);
 	return ret;
-- 
2.39.5 (Apple Git-154)

Re: [PATCH] accel/amdxdna: Fix use-after-free in amdxdna_gem_dmabuf_mmap()

[Lizhi Hou]

On 6/25/26 04:32, Wentao Liang wrote:
> When vm_insert_pages() fails, the error path calls vma->vm_ops->close(vma)
> which internally calls drm_gem_vm_close() → drm_gem_object_put(),
> releasing the GEM object reference acquired at the start of the function.
> However, the close_vma label then falls through to put_obj, which calls
> drm_gem_object_put() a second time on the same object.
>
> If the first put releases the last reference, the object is freed and the
> second put accesses freed memory, causing a use-after-free.
>
> Fix by returning directly from close_vma instead of falling through to
> put_obj, since the close handler already performs all necessary cleanup
> including the object put.
>
> Cc: stable@vger.kernel.org
> Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>   drivers/accel/amdxdna/amdxdna_gem.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
> index 6e367ddb9e1b..fec9763c518c 100644
> --- a/drivers/accel/amdxdna/amdxdna_gem.c
> +++ b/drivers/accel/amdxdna/amdxdna_gem.c
> @@ -469,6 +469,7 @@ static int amdxdna_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struc
>   
>   close_vma:
>   	vma->vm_ops->close(vma);
> +	return ret;
Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>
>   put_obj:
>   	drm_gem_object_put(gobj);
>   	return ret;

Re: [PATCH] accel/amdxdna: Fix use-after-free in amdxdna_gem_dmabuf_mmap()

[Lizhi Hou]

Applied to drm-misc-fixes

On 6/26/26 09:47, Lizhi Hou wrote:
>
> On 6/25/26 04:32, Wentao Liang wrote:
>> When vm_insert_pages() fails, the error path calls 
>> vma->vm_ops->close(vma)
>> which internally calls drm_gem_vm_close() → drm_gem_object_put(),
>> releasing the GEM object reference acquired at the start of the 
>> function.
>> However, the close_vma label then falls through to put_obj, which calls
>> drm_gem_object_put() a second time on the same object.
>>
>> If the first put releases the last reference, the object is freed and 
>> the
>> second put accesses freed memory, causing a use-after-free.
>>
>> Fix by returning directly from close_vma instead of falling through to
>> put_obj, since the close handler already performs all necessary cleanup
>> including the object put.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
>> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
>> ---
>>   drivers/accel/amdxdna/amdxdna_gem.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/accel/amdxdna/amdxdna_gem.c 
>> b/drivers/accel/amdxdna/amdxdna_gem.c
>> index 6e367ddb9e1b..fec9763c518c 100644
>> --- a/drivers/accel/amdxdna/amdxdna_gem.c
>> +++ b/drivers/accel/amdxdna/amdxdna_gem.c
>> @@ -469,6 +469,7 @@ static int amdxdna_gem_dmabuf_mmap(struct dma_buf 
>> *dma_buf, struct vm_area_struc
>>     close_vma:
>>       vma->vm_ops->close(vma);
>> +    return ret;
> Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>
>>   put_obj:
>>       drm_gem_object_put(gobj);
>>       return ret;