Re: [PATCH] drm/amdgpu: check a user-provided number of BOs in list

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

Coming back to the original patch.

Am 08.04.25 um 11:17 schrieb Denis Arefev:
> The user can set any value to the variable ‘bo_number’, via the ioctl
> command DRM_IOCTL_AMDGPU_BO_LIST. This will affect the arithmetic
> expression ‘in->bo_number * in->bo_info_size’, which is prone to
> overflow. Add a valid value check.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 964d0fbf6301 ("drm/amdgpu: Allow to create BO lists in CS ioctl v3")
> Cc: stable@vger.kernel.org
> Signed-off-by: Denis Arefev <arefev@swemel.ru>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> index 702f6610d024..dd30d2426ff7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> @@ -189,6 +189,9 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
>  	struct drm_amdgpu_bo_list_entry *info;
>  	int r;
>  
> +	if (!in->bo_number || in->bo_number > UINT_MAX / info_size)
> +		return -EINVAL;
> +

As discussed with Linus the goal here is not to avoid the warning, but rather to apply a reasonable limit.

Since we already use an u16 for the number of BOs in other cases it is probably reasonable to assume that we will never have more than USHRT_MAX number of BOs here as well.

So please change the patch accordingly and hopefully nobody will complain.

Regards,
Christian.

>  	info = kvmalloc_array(in->bo_number, info_size, GFP_KERNEL);
>  	if (!info)
>  		return -ENOMEM;