linux-kernel - [PATCH 2/3] vfs - fix dentry ref count in do

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Date:	Tue, 18 Jan 2011 12:06:10 +0800
From:	Ian Kent <raven@...maw.net>
To:	Nick Piggin <npiggin@...e.de>, David Howells <dhowells@...hat.com>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 2/3] vfs - fix dentry ref count in do_lookup()

There is a ref count problem in fs/namei.c:do_lookup().

When walking in ref-walk mode, if follow_managed() returns a fail the
reference held by path.dentry isn't dropped.
---

 fs/namei.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index b753192..dbc36ff 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1272,8 +1272,11 @@ done:
 	path->mnt = mnt;
 	path->dentry = dentry;
 	err = follow_managed(path, nd->flags);
-	if (unlikely(err < 0))
+	if (unlikely(err < 0)) {
+		if (!(nd->flags & LOOKUP_RCU))
+			dput(dentry);
 		return err;
+	}
 	*inode = path->dentry->d_inode;
 	return 0;
 

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