From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120608041845.945062242@decadent.org.uk> Date: Fri, 08 Jun 2012 05:19:18 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andreas Dilger , "Theodore Tso" Subject: [ 38/82] ext4: disallow hard-linked directory in ext4_lookup In-Reply-To: <20120608041840.861504477@decadent.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andreas Dilger commit 7e936b737211e6b54e34b71a827e56b872e958d8 upstream. A hard-linked directory to its parent can cause the VFS to deadlock, and is a sign of a corrupted file system. So detect this case in ext4_lookup(), before the rmdir() lockup scenario can take place. Signed-off-by: Andreas Dilger Signed-off-by: "Theodore Ts'o" Signed-off-by: Ben Hutchings --- fs/ext4/namei.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index a9fd5f4..daf8260 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1330,6 +1330,12 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, stru EXT4_ERROR_INODE(dir, "bad inode number: %u", ino); return ERR_PTR(-EIO); } + if (unlikely(ino == dir->i_ino)) { + EXT4_ERROR_INODE(dir, "'%.*s' linked to parent dir", + dentry->d_name.len, + dentry->d_name.name); + return ERR_PTR(-EIO); + } inode = ext4_iget(dir->i_sb, ino); if (inode == ERR_PTR(-ESTALE)) { EXT4_ERROR_INODE(dir,