apparmor: release exe file resources on path failure

get_current_exe_path() takes both an exe_file reference and a path
reference before resolving the path name. If aa_path_name() failed, it
returned immediately and leaked both references.

Route the failure through the common cleanup path so fput() and path_put()
always run after the references are acquired.

Fixes: 8d34e16f7f ("apparmor: userns: Add support for execpath in userns")
Reviewed-by: Ryan Lee <[email protected]>
Signed-off-by: Zygmunt Krynicki <[email protected]>
Signed-off-by: John Johansen <[email protected]>

security/apparmor/task.c

@@ -313,9 +313,12 @@ static const char *get_current_exe_path(char *buffer, int buffer_size)
 	p = exe_file->f_path;
 	path_get(&p);
 
-	if (aa_path_name(&p, FLAG_VIEW_SUBNS, buffer, &path_str, NULL, NULL))
-		return ERR_PTR(-ENOMEM);
+	if (aa_path_name(&p, FLAG_VIEW_SUBNS, buffer, &path_str, NULL, NULL)) {
+		path_str = ERR_PTR(-ENOMEM);
+		goto out;
+	}
 
+out:
 	fput(exe_file);
 	path_put(&p);