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

[ Upstream commit 47cfdc338d ]

 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>
pull/1175/head
Immad Mir 2023-06-23 19:14:01 +05:30 committed by Greg Kroah-Hartman
parent da0a7c6975
commit 3e5eb6c5ec
1 changed files with 5 additions and 0 deletions
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5
fs/jfs/namei.c
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@ -799,6 +799,11 @@ 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);