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affs_lookup(): close a race with affs_remove_link()

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commit 30da870ce4a4e007c901858a96e9e394a1daa74a 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 2871a70132
commit 1e5edf32e4
1 changed files with 7 additions and 3 deletions
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10
fs/affs/namei.c
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@ -206,9 +206,10 @@ 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;
@ -222,10 +223,13 @@ 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;
}