linux-kernel - [22/70] net ipv6: Fix duplicate /proc/sys/net/ipv6/neigh directory entries.

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Date:	Tue, 19 Apr 2011 13:08:31 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	"Eric W. Biederman" <ebiederm@...stanetworks.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [22/70] net ipv6: Fix duplicate /proc/sys/net/ipv6/neigh directory entries.

2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Eric W. Biederman <ebiederm@...stanetworks.com>

[ Upstream commit 9d2a8fa96a44ba242de3a6f56acaef7a40a97b97 ]

When I was fixing issues with unregisgtering tables under /proc/sys/net/ipv6/neigh
by adding a mount point it appears I missed a critical ordering issue, in the
ipv6 initialization.  I had not realized that ipv6_sysctl_register is called
at the very end of the ipv6 initialization and in particular after we call
neigh_sysctl_register from ndisc_init.

"neigh" needs to be initialized in ipv6_static_sysctl_register which is
the first ipv6 table to initialized, and definitely before ndisc_init.
This removes the weirdness of duplicate tables while still providing a
"neigh" mount point which prevents races in sysctl unregistering.

This was initially reported at https://bugzilla.kernel.org/show_bug.cgi?id=31232
Reported-by: sunkan@...pa.cx
Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 net/ipv6/sysctl_net_ipv6.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -17,6 +17,16 @@
 
 static struct ctl_table empty[1];
 
+static ctl_table ipv6_static_skeleton[] = {
+	{
+		.procname	= "neigh",
+		.maxlen		= 0,
+		.mode		= 0555,
+		.child		= empty,
+	},
+	{ }
+};
+
 static ctl_table ipv6_table_template[] = {
 	{
 		.procname	= "route",
@@ -37,12 +47,6 @@ static ctl_table ipv6_table_template[] =
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{
-		.procname	= "neigh",
-		.maxlen		= 0,
-		.mode		= 0555,
-		.child		= empty,
-	},
 	{ }
 };
 
@@ -160,7 +164,7 @@ static struct ctl_table_header *ip6_base
 
 int ipv6_static_sysctl_register(void)
 {
-	ip6_base = register_sysctl_paths(net_ipv6_ctl_path, empty);
+	ip6_base = register_sysctl_paths(net_ipv6_ctl_path, ipv6_static_skeleton);
 	if (ip6_base == NULL)
 		return -ENOMEM;
 	return 0;


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