From: Andrea Righi <andrea.righi@canonical.com>
Date: Sun, 21 May 2023 08:28:13 +0000 (+0200)
Subject: ovl: validate superblock in OVL_FS()
X-Git-Tag: v6.6-rc1~140^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=adcd459ff805ce5e11956cfa1e9aa85471b6ae8d;p=thirdparty%2Fkernel%2Fstable.git

ovl: validate superblock in OVL_FS()

When CONFIG_OVERLAY_FS_DEBUG is enabled add an explicit check to make
sure that OVL_FS() is always used with a valid overlayfs superblock.
Otherwise trigger a WARN_ON_ONCE().

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index edb457544b5f6..e9539f98e86a4 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -121,6 +121,9 @@ extern struct file_system_type ovl_fs_type;
 
 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
 {
+	if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
+		WARN_ON_ONCE(sb->s_type != &ovl_fs_type);
+
 	return (struct ovl_fs *)sb->s_fs_info;
 }