From: Aristeu Rozanski <arozansk@redhat.com>
Date: Fri, 8 Feb 2008 00:27:42 -0500
Subject: [net] sctp: add bind hash locking to migrate code
Message-id: 20080208052742.GE968@redhat.com
O-Subject: [RHEL5.2 PATCH] sctp: prevent slab corruption on sctp_sock_migrate()
Bugzilla: 426234

https://bugzilla.redhat.com/show_bug.cgi?id=426234

This patch is resolves a test blocker for gfs/gfs2 test tool when the tool is
using sctp to communicate between nodes.

Testing: the patch has already been tested by cluster testing group and resolves the problem.

Upstream: f26f7c480555812ca7c4037e0a50fa54afe2cb4a

Brew build id: 1159386

---------

[SCTP]: Add bind hash locking to the migrate code

SCTP accept code tries to add a newliy created socket
to a bind bucket without holding a lock.   On a really
busy system, that can causes slab corruptions.
Add a lock around this code.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index ea00465..9adc06f 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5662,6 +5662,7 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 	struct sctp_endpoint *newep = newsp->ep;
 	struct sk_buff *skb, *tmp;
 	struct sctp_ulpevent *event;
+	struct sctp_bind_hashbucket *head;
 	int flags = 0;
 
 	/* Migrate socket buffer sizes and all the socket level options to the
@@ -5679,10 +5680,15 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 	newsp->hmac = NULL;
 
 	/* Hook this new socket in to the bind_hash list. */
+	head = &sctp_port_hashtable[sctp_phashfn(inet_sk(oldsk)->num)];
+	sctp_local_bh_disable();
+	sctp_spin_lock(&head->lock);
 	pp = sctp_sk(oldsk)->bind_hash;
 	sk_add_bind_node(newsk, &pp->owner);
 	sctp_sk(newsk)->bind_hash = pp;
 	inet_sk(newsk)->num = inet_sk(oldsk)->num;
+	sctp_spin_unlock(&head->lock);
+	sctp_local_bh_enable();
 
 	/* Copy the bind_addr list from the original endpoint to the new
 	 * endpoint so that we can handle restarts properly