Re: [PATCH v2] drm/amdgpu: Limit BO list entry count to prevent resource exhaustion

["Christian König" <christian.koenig@amd.com>]

On 3/12/26 11:13, Jesse.Zhang wrote:
> Userspace can pass an arbitrary number of BO list entries via the
> bo_number field. Although the previous multiplication overflow check
> prevents out-of-bounds allocation, a large number of entries could still
> cause excessive memory allocation (up to potentially gigabytes) and
> unnecessarily long list processing times.
> 
> Introduce a hard limit of 128k entries per BO list, which is more than
> sufficient for any realistic use case (e.g., a single list containing all
> buffers in a large scene). This prevents memory exhaustion attacks and
> ensures predictable performance.
> 
> Return -EINVAL if the requested entry count exceeds the limit
> 
> Suggested-by: Christian König <christian.koenig@amd.com>
> Signed-off-by: Jesse Zhang <jesse.zhang@amd.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> index 87ec46c56a6e..3270ea50bdc7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> @@ -36,6 +36,7 @@
>  
>  #define AMDGPU_BO_LIST_MAX_PRIORITY	32u
>  #define AMDGPU_BO_LIST_NUM_BUCKETS	(AMDGPU_BO_LIST_MAX_PRIORITY + 1)
> +#define AMDGPU_BO_LIST_MAX_ENTRIES	(128 * 1024)
>  
>  static void amdgpu_bo_list_free_rcu(struct rcu_head *rcu)
>  {
> @@ -188,6 +189,9 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
>  	const uint32_t bo_number = in->bo_number;
>  	struct drm_amdgpu_bo_list_entry *info;
>  
> +	if (bo_number > AMDGPU_BO_LIST_MAX_ENTRIES)
> +		return -EINVAL;
> +
>  	/* copy the handle array from userspace to a kernel buffer */
>  	if (likely(info_size == bo_info_size)) {
>  		info = vmemdup_array_user(uptr, bo_number, info_size);