drm/amdgpu: add missing size check in amdgpu_debugfs_gprwave_read()

Avoid a possible buffer overflow if size is larger than 4K.

Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit f5d873f)
Cc: stable@vger.kernel.org

Author: alexdeucher

drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c

@@ -402,7 +402,7 @@ static ssize_t amdgpu_debugfs_gprwave_read(struct file *f, char __user *buf, siz
 	int r;
 	uint32_t *data, x;
 
-	if (size & 0x3 || *pos & 0x3)
+	if (size > 4096 || size & 0x3 || *pos & 0x3)
 		return -EINVAL;
 
 	r = pm_runtime_get_sync(adev_to_drm(adev)->dev);