drm/amdgpu: double free error and freeing uninitialized null pointer

Fix a double free and an uninitialized pointer read error. Both tmp and
new are pointing at same address and both are freed which leads to
double free. Adding a check to verify if new and tmp are free in the
error_free label fixes the double free issue. new is not initialized to
null which also leads to a free on an uninitialized pointer.
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Suggested by: S. Amaranath <Amaranath.Somalapuram@amd.com>
Signed-off-by: Sebin Sebastian <mailmesebin00@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1705,7 +1705,7 @@ static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)file_inode(f)->i_private;
 	char reg_offset[11];
-	uint32_t *new, *tmp = NULL;
+	uint32_t *new = NULL, *tmp = NULL;
 	int ret, i = 0, len = 0;
 
 	do {
@@ -1747,7 +1747,8 @@ static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
 	ret = size;
 
 error_free:
-	kfree(tmp);
+	if (tmp != new)
+		kfree(tmp);
 	kfree(new);
 	return ret;
 }