affs_lookup(): close a race with affs_remove_link()

commit 30da870ce4 upstream.

we unlock the directory hash too early - if we are looking at secondary
link and primary (in another directory) gets removed just as we unlock,
we could have the old primary moved in place of the secondary, leaving
us to look into freed entry (and leaving our dentry with ->d_fsdata
pointing to a freed entry).

Cc: stable@vger.kernel.org # 2.4.4+
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Al Viro 2018-05-06 12:15:20 -04:00 committed by Greg Kroah-Hartman
parent 211922cfb2
commit 5aba1dc0d5
1 changed files with 7 additions and 3 deletions

View File

@ -224,9 +224,10 @@ affs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
affs_lock_dir(dir);
bh = affs_find_entry(dir, dentry);
affs_unlock_dir(dir);
if (IS_ERR(bh))
if (IS_ERR(bh)) {
affs_unlock_dir(dir);
return ERR_CAST(bh);
}
if (bh) {
u32 ino = bh->b_blocknr;
@ -240,10 +241,13 @@ affs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
}
affs_brelse(bh);
inode = affs_iget(sb, ino);
if (IS_ERR(inode))
if (IS_ERR(inode)) {
affs_unlock_dir(dir);
return ERR_CAST(inode);
}
}
d_add(dentry, inode);
affs_unlock_dir(dir);
return NULL;
}