From: Jun Nie <jun.nie@xxxxxxxxxx> commit f31173c19901a96bb2ebf6bcfec8a08df7095c91 upstream. The ea block expansion need to access s_root while it is already set as NULL when umount is triggered. Refuse this request to avoid panic. Reported-by: syzbot+2dacb8f015bf1420155f@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?id=3613786cb88c93aa1c6a279b1df6a7b201347d08 Link: https://lore.kernel.org/r/20230103014517.495275-3-jun.nie@xxxxxxxxxx Cc: stable@xxxxxxxxxx Signed-off-by: Jun Nie <jun.nie@xxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/xattr.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1436,6 +1436,13 @@ static struct inode *ext4_xattr_inode_cr uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) }; int err; + if (inode->i_sb->s_root == NULL) { + ext4_warning(inode->i_sb, + "refuse to create EA inode when umounting"); + WARN_ON(1); + return ERR_PTR(-EINVAL); + } + /* * Let the next inode be the goal, so we try and allocate the EA inode * in the same group, or nearby one.
