ext4: don't orphan or truncate the boot loader inode

commit e2bfb088fac03c0f621886a04cffc7faa2b49b1d upstream.

The boot loader inode (inode #5) should never be visible in the
directory hierarchy, but it's possible if the file system is corrupted
that there will be a directory entry that points at inode #5.  In
order to avoid accidentally trashing it, when such a directory inode
is opened, the inode will be marked as a bad inode, so that it's not
possible to modify (or read) the inode from userspace.

Unfortunately, when we unlink this (invalid/illegal) directory entry,
we will put the bad inode on the ophan list, and then when try to
unlink the directory, we don't actually remove the bad inode from the
orphan list before freeing in-memory inode structure.  This means the
in-memory orphan list is corrupted, leading to a kernel oops.

In addition, avoid truncating a bad inode in ext4_destroy_inode(),
since truncating the boot loader inode is not a smart thing to do.

Reported-by: Sami Liedes <sami.liedes@iki.fi>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8c100a87b69557f5ab9e1c5502d064838e5e4f61..05ce4581ab6f61e71913863ca66821d1fa854262 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -224,16 +224,15 @@ void ext4_evict_inode(struct inode *inode)
                goto no_delete;
        }
 
-       if (!is_bad_inode(inode))
-               dquot_initialize(inode);
+       if (is_bad_inode(inode))
+               goto no_delete;
+       dquot_initialize(inode);
 
        if (ext4_should_order_data(inode))
                ext4_begin_ordered_truncate(inode, 0);
        truncate_inode_pages_final(&inode->i_data);
 
        WARN_ON(atomic_read(&EXT4_I(inode)->i_ioend_count));
-       if (is_bad_inode(inode))
-               goto no_delete;
 
        /*
         * Protect us against freezing - iput() caller didn't have to have any

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 634b9dc31b82189c4cf428d1c079b573e5175334..bb9030a2a30d7004ca01e6ace90572bf79f1adb1 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2573,7 +2573,7 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode)
        int err = 0, rc;
        bool dirty = false;
 
-       if (!sbi->s_journal)
+       if (!sbi->s_journal || is_bad_inode(inode))
                return 0;
 
        WARN_ON_ONCE(!(inode->i_state & (I_NEW | I_FREEING)) &&