linux-kernel - [PATCH 4.2.y-ckt 103/305] Don't reset ->total_link_count on nested calls of vfs_path

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Date:	Fri, 15 Jan 2016 15:58:37 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 103/305] Don't reset ->total_link_count on nested calls of vfs_path_lookup()

4.2.8-ckt2 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit 2788cc47f4593cca2c3c73c7bb82cd32b88c8ef7 upstream.

we already zero it on outermost set_nameidata(), so initialization in
path_init() is pointless and wrong.  The same DoS exists on pre-4.2
kernels, but there a slightly different fix will be needed.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 fs/namei.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/namei.c b/fs/namei.c
index 36df481..f39a798 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1999,7 +1999,6 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
 	nd->last_type = LAST_ROOT; /* if there are only slashes... */
 	nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
 	nd->depth = 0;
-	nd->total_link_count = 0;
 	if (flags & LOOKUP_ROOT) {
 		struct dentry *root = nd->root.dentry;
 		struct inode *inode = root->d_inode;
-- 
1.9.1