On Fri, 2023-06-02 at 02:17 -0700, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch and the reproducer did not trigger any issue:
>
> Reported-and-tested-by: syzbot+8fb64a61fdd96b50f3b8@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> Tested on:
>
> commit: 4432b507 lsm: fix a number of misspellings
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm.git next
> console output: https://syzkaller.appspot.com/x/log.txt?x=166c541d280000
> kernel config: https://syzkaller.appspot.com/x/.config?x=38526bf24c8d961b
> dashboard link: https://syzkaller.appspot.com/bug?extid=8fb64a61fdd96b50f3b8
> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
> patch: https://syzkaller.appspot.com/x/patch.diff?x=1095cd79280000
>
> Note: testing is done by a robot and is best-effort only.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm.git next
From 73bb02eb7a751c447af43d7cac7c191329b6dd55 Mon Sep 17 00:00:00 2001
From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Date: Fri, 2 Jun 2023 10:10:28 +0200
Subject: [PATCH] reiserfs: Disable by default security xattr init since it
never worked
Commit d82dcd9e21b7 ("reiserfs: Add security prefix to xattr name in
reiserfs_security_write()"), while fixed the security xattr initialization,
it also revealed a circular locking dependency between the reiserfs write
lock and the inode lock.
Add the new config option CONFIG_REISERFS_FS_SECURITY_INIT to
enable/disable the feature. Also, since the bug in security xattr
initialization was introduced since the beginning, disable it by default.
Reported-and-tested-by: syzbot+8fb64a61fdd96b50f3b8@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=8fb64a61fdd96b50f3b8
Suggested-by: Jeff Mahoney <jeffm@xxxxxxxx>
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
fs/reiserfs/Kconfig | 15 +++++++++++++++
fs/reiserfs/super.c | 3 +++
fs/reiserfs/xattr_security.c | 3 +++
3 files changed, 21 insertions(+)
diff --git a/fs/reiserfs/Kconfig b/fs/reiserfs/Kconfig
index 4d22ecfe0fa..a618d0bda7b 100644
--- a/fs/reiserfs/Kconfig
+++ b/fs/reiserfs/Kconfig
@@ -88,3 +88,18 @@ config REISERFS_FS_SECURITY
If you are not using a security module that requires using
extended attributes for file security labels, say N.
+
+config REISERFS_FS_SECURITY_INIT
+ bool "ReiserFS Security Labels initialization"
+ depends on REISERFS_FS_XATTR
+ default false
+ help
+ Init new inodes with security labels provided by LSMs.
+
+ It was broken from the beginning, since the xattr name was
+ missing the 'security.' prefix.
+
+ Enabling this option might cause lockdep warnings and
+ ultimately deadlocks.
+
+ If unsure, say N.
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 929acce6e73..b427d03d0ea 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1654,6 +1654,9 @@ static int read_super_block(struct super_block *s, int offset)
reiserfs_warning(NULL, "", "reiserfs filesystem is deprecated and "
"scheduled to be removed from the kernel in 2025");
+ if (IS_ENABLED(CONFIG_REISERFS_FS_SECURITY_INIT))
+ reiserfs_warning(NULL, "", "initializing security xattrs can cause deadlocks");
+
SB_BUFFER_WITH_SB(s) = bh;
SB_DISK_SUPER_BLOCK(s) = rs;
diff --git a/fs/reiserfs/xattr_security.c b/fs/reiserfs/xattr_security.c
index 078dd8cc312..d82c4507803 100644
--- a/fs/reiserfs/xattr_security.c
+++ b/fs/reiserfs/xattr_security.c
@@ -69,6 +69,9 @@ int reiserfs_security_init(struct inode *dir, struct inode *inode,
sec->value = NULL;
sec->length = 0;
+ if (!IS_ENABLED(CONFIG_REISERFS_FS_SECURITY_INIT))
+ return 0;
+
/* Don't add selinux attributes on xattrs - they'll never get used */
if (IS_PRIVATE(dir))
return 0;
--
2.25.1
