From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro Subject: [PATCH 4.6 041/203] autofs braino fix for do_last() Date: Mon, 25 Jul 2016 13:54:16 -0700 Message-Id: <20160725203430.944201746@linuxfoundation.org> In-Reply-To: <20160725203429.221747288@linuxfoundation.org> References: <20160725203429.221747288@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit e6ec03a25f12b312b7e0c037fe4a6471c4ee5665 upstream. It's an analogue of commit 7500c38a (fix the braino in "namei: massage lookup_slow() to be usable by lookup_one_len_unlocked()"). The same problem (->lookup()-returned unhashed negative dentry just might be an autofs one with ->d_manage() that would wait until the daemon makes it positive) applies in do_last() - we need to do follow_managed() first. Fortunately, remaining callers of follow_managed() are OK - only autofs has that weirdness (negative dentry that does not mean an instant -ENOENT)) and autofs never has its negative dentries hashed, so we can't pick one from a dcache lookup. ->d_manage() is a bloody mess ;-/ Spotted-by: Ian Kent Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/fs/namei.c +++ b/fs/namei.c @@ -3173,6 +3173,10 @@ retry_lookup: got_write = false; } + error = follow_managed(&path, nd); + if (unlikely(error < 0)) + return error; + if (unlikely(d_is_negative(path.dentry))) { path_to_nameidata(&path, nd); return -ENOENT; @@ -3188,10 +3192,6 @@ retry_lookup: return -EEXIST; } - error = follow_managed(&path, nd); - if (unlikely(error < 0)) - return error; - seq = 0; /* out of RCU mode, so the value doesn't matter */ inode = d_backing_inode(path.dentry); finish_lookup: