Re: [PATCH 1/2] drm/xe: Validate user fence during creation

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 7/17/2024 4:04 PM, Matthew Brost wrote:
> Fail invalidate addresses during user fence creation.
>
> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>


> ---
>   drivers/gpu/drm/xe/xe_sync.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
> index 2883d9aca404..f2e5e3c8c0cd 100644
> --- a/drivers/gpu/drm/xe/xe_sync.c
> +++ b/drivers/gpu/drm/xe/xe_sync.c
> @@ -53,14 +53,18 @@ static struct xe_user_fence *user_fence_create(struct xe_device *xe, u64 addr,
>   					       u64 value)
>   {
>   	struct xe_user_fence *ufence;
> +	u64 __user *ptr = u64_to_user_ptr(addr);
> +
> +	if (!access_ok(ptr, sizeof(ptr)))
> +		return ERR_PTR(-EFAULT);
>   
>   	ufence = kmalloc(sizeof(*ufence), GFP_KERNEL);
>   	if (!ufence)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>   
>   	ufence->xe = xe;
>   	kref_init(&ufence->refcount);
> -	ufence->addr = u64_to_user_ptr(addr);
> +	ufence->addr = ptr;
>   	ufence->value = value;
>   	ufence->mm = current->mm;
>   	mmgrab(ufence->mm);
> @@ -183,8 +187,8 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>   		} else {
>   			sync->ufence = user_fence_create(xe, sync_in.addr,
>   							 sync_in.timeline_value);
> -			if (XE_IOCTL_DBG(xe, !sync->ufence))
> -				return -ENOMEM;
> +			if (XE_IOCTL_DBG(xe, IS_ERR(sync->ufence)))
> +				return PTR_ERR(sync->ufence);
>   		}
>   
>   		break;