Return-Path: From: Greg Kroah-Hartman Subject: [PATCH 4.4 317/342] should_follow_link(): validate ->d_seq after having decided to follow To: Cc: Greg Kroah-Hartman , , Al Viro Message-Id: <20160301234538.121370124@linuxfoundation.org> In-Reply-To: <20160301234527.990448862@linuxfoundation.org> References: <20160301234527.990448862@linuxfoundation.org> Date: Tue, 01 Mar 2016 23:55:30 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit a7f775428b8f5808815c0e3004020cedb94cbe3b upstream. ... otherwise d_is_symlink() above might have nothing to do with the inode value we've got. Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/namei.c +++ b/fs/namei.c @@ -1711,6 +1711,11 @@ static inline int should_follow_link(str return 0; if (!follow) return 0; + /* make sure that d_is_symlink above matches inode */ + if (nd->flags & LOOKUP_RCU) { + if (read_seqcount_retry(&link->dentry->d_seq, seq)) + return -ECHILD; + } return pick_link(nd, link, inode, seq); }