Commit a7d17d6b authored Jun 23, 2023 by Immad Mir Committed by Greg Kroah-Hartman Aug 30, 2023

FS: JFS: Fix null-ptr-deref Read in txBegin



[ Upstream commit 47cfdc338d674d38f4b2f22b7612cc6a2763ba27 ]

 Syzkaller reported an issue where txBegin may be called
 on a superblock in a read-only mounted filesystem which leads
 to NULL pointer deref. This could be solved by checking if
 the filesystem is read-only before calling txBegin, and returning
 with appropiate error code.

Reported-By:  <syzbot+f1faa20eec55e0c8644c@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?id=be7e52c50c5182cc09a09ea6fc456446b2039de3



Signed-off-by: Immad Mir <mirimmad17@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 2225000d

fs/jfs/namei.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -798,6 +798,11 @@ static int jfs_link(struct dentry *old_dentry,
		if (rc)
		goto out;

		if (isReadOnly(ip)) {
		jfs_error(ip->i_sb, "read-only filesystem\n");
		return -EROFS;
		}

		tid = txBegin(ip->i_sb, 0);

		mutex_lock_nested(&JFS_IP(dir)->commit_mutex, COMMIT_MUTEX_PARENT);