[PATCH] nouveau/u_memcpya: use vmemdup_user

[Danilo Krummrich]

On 8/10/23 20:50, Dave Airlie wrote:
> From: Dave Airlie <airlied at redhat.com>
> 
> I think there are limit checks in places for most things but the
> new api wants to not have them.
> 
> Add a limit check and use the vmemdup_user helper instead.

Reviewed-by: Danilo Krummrich <dakr at redhat.com>

> 
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>   drivers/gpu/drm/nouveau/nouveau_drv.h | 19 +++++--------------
>   1 file changed, 5 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
> index 54063b094a69..8a7357688aff 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drv.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
> @@ -189,21 +189,12 @@ u_free(void *addr)
>   static inline void *
>   u_memcpya(uint64_t user, unsigned nmemb, unsigned size)
>   {
> -	void *mem;
> -	void __user *userptr = (void __force __user *)(uintptr_t)user;
> +	void __user *userptr = u64_to_user_ptr(user);
> +	size_t bytes;
>   
> -	size *= nmemb;
> -
> -	mem = kvmalloc(size, GFP_KERNEL);
> -	if (!mem)
> -		return ERR_PTR(-ENOMEM);
> -
> -	if (copy_from_user(mem, userptr, size)) {
> -		u_free(mem);
> -		return ERR_PTR(-EFAULT);
> -	}
> -
> -	return mem;
> +	if (unlikely(check_mul_overflow(nmemb, size, &bytes)))
> +		return NULL;
> +	return vmemdup_user(userptr, bytes);
>   }
>   
>   #include <nvif/object.h>