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From: Anmol Karn <anmol.karan123@gmail.com>
To: jack@suse.cz, jeffm@suse.com
Cc: linux-kernel@vger.kernel.org, reiserfs-devel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	syzkaller-bugs@googlegroups.com, anmol.karan123@gmail.com,
	syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com
Subject: [Linux-kernel-mentees] [PATCH] fs: reiserfs: xattr: Fix null pointer derefernce in open_xa_root()
Date: Thu,  1 Oct 2020 14:35:47 +0530	[thread overview]
Message-ID: <20201001090547.431840-1-anmol.karan123@gmail.com> (raw)

d_really_is_negative() checks for the dentry->d_inode whether it's NULL or not, 
but in open_xa_root(), when it checks 'privroot->d_inode', it doesn't check whether
privroot is NULL or not, this leads to a null pointer dereference while calling it 
from open_xa_dir() while initializing xaroot.

- fs/reiserfs/xattr.c
The bug seems to get triggered at this line:
	
if (d_really_is_negative(privroot))
		return ERR_PTR(-EOPNOTSUPP);

Fix it by adding a NULL check for privroot. 

Reported-and-tested-by: syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com 
Link: https://syzkaller.appspot.com/bug?extid=9b33c9b118d77ff59b6f 
Signed-off-by: Anmol Karn <anmol.karan123@gmail.com>
---
 fs/reiserfs/xattr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 28b241cd6987..a75480d0ee7e 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -121,8 +121,9 @@ static struct dentry *open_xa_root(struct super_block *sb, int flags)
 	struct dentry *privroot = REISERFS_SB(sb)->priv_root;
 	struct dentry *xaroot;
 
-	if (d_really_is_negative(privroot))
+	if (!privroot || d_really_is_negative(privroot)) {
 		return ERR_PTR(-EOPNOTSUPP);
+	}
 
 	inode_lock_nested(d_inode(privroot), I_MUTEX_XATTR);
 
-- 
2.28.0


WARNING: multiple messages have this Message-ID (diff)
From: Anmol Karn <anmol.karan123@gmail.com>
To: jack@suse.cz, jeffm@suse.com
Cc: syzkaller-bugs@googlegroups.com,
	syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com,
	linux-kernel@vger.kernel.org, reiserfs-devel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH] fs: reiserfs: xattr: Fix null pointer derefernce in open_xa_root()
Date: Thu,  1 Oct 2020 14:35:47 +0530	[thread overview]
Message-ID: <20201001090547.431840-1-anmol.karan123@gmail.com> (raw)

d_really_is_negative() checks for the dentry->d_inode whether it's NULL or not, 
but in open_xa_root(), when it checks 'privroot->d_inode', it doesn't check whether
privroot is NULL or not, this leads to a null pointer dereference while calling it 
from open_xa_dir() while initializing xaroot.

- fs/reiserfs/xattr.c
The bug seems to get triggered at this line:
	
if (d_really_is_negative(privroot))
		return ERR_PTR(-EOPNOTSUPP);

Fix it by adding a NULL check for privroot. 

Reported-and-tested-by: syzbot+9b33c9b118d77ff59b6f@syzkaller.appspotmail.com 
Link: https://syzkaller.appspot.com/bug?extid=9b33c9b118d77ff59b6f 
Signed-off-by: Anmol Karn <anmol.karan123@gmail.com>
---
 fs/reiserfs/xattr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 28b241cd6987..a75480d0ee7e 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -121,8 +121,9 @@ static struct dentry *open_xa_root(struct super_block *sb, int flags)
 	struct dentry *privroot = REISERFS_SB(sb)->priv_root;
 	struct dentry *xaroot;
 
-	if (d_really_is_negative(privroot))
+	if (!privroot || d_really_is_negative(privroot)) {
 		return ERR_PTR(-EOPNOTSUPP);
+	}
 
 	inode_lock_nested(d_inode(privroot), I_MUTEX_XATTR);
 
-- 
2.28.0

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

             reply	other threads:[~2020-10-01  9:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01  9:05 Anmol Karn [this message]
2020-10-01  9:05 ` [Linux-kernel-mentees] [PATCH] fs: reiserfs: xattr: Fix null pointer derefernce in open_xa_root() Anmol Karn
2020-10-01  9:28 ` Jan Kara
2020-10-01  9:28   ` Jan Kara
2020-10-01 10:44   ` Anmol karn
2020-10-01 10:44     ` Anmol karn

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