Patch "IB/ipoib: Fix memory corruption in ipoib cm mode connect flow" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

IB/ipoib: Fix memory corruption in ipoib cm mode connect flow

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-ipoib-fix-memory-corruption-in-ipoib-cm-mode-connect-flow.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Erez Shitrit <[email protected]>
Date: Sun, 28 Aug 2016 10:58:31 +0300
Subject: IB/ipoib: Fix memory corruption in ipoib cm mode connect flow

From: Erez Shitrit <[email protected]>

commit 546481c2816ea3c061ee9d5658eb48070f69212e upstream.

When a new CM connection is being requested, ipoib driver copies data from the path pointer in the CM/tx object, the path object might be invalid at the point and memory corruption will happened later when now the CM driver will try using that data.

The next scenario demonstrates it:

	neigh_add_path --> ipoib_cm_create_tx -->
	queue_work (pointer to path is in the cm/tx struct)
	#while the work is still in the queue,
	#the port goes down and causes the ipoib_flush_paths:
	ipoib_flush_paths --> path_free --> kfree(path)
	#at this point the work scheduled starts.
	ipoib_cm_tx_start --> copy from the (invalid)path pointer:
	(memcpy(&pathrec, &p->path->pathrec, sizeof pathrec);)
	 -> memory corruption.

To fix that the driver now starts the CM/tx connection only if that specific path exists in the general paths database.
This check is protected with the relevant locks, and uses the gid from the neigh member in the CM/tx object which is valid according to the ref count that was taken by the CM/tx.

---
 drivers/infiniband/ulp/ipoib/ipoib.h      |    1 +
 drivers/infiniband/ulp/ipoib/ipoib_cm.c   |   16 ++++++++++++++++
 drivers/infiniband/ulp/ipoib/ipoib_main.c |    2 +-
 3 files changed, 18 insertions(+), 1 deletion(-)

@@ -478,6 +478,7 @@ void ipoib_send(struct net_device *dev,
 		struct ipoib_ah *address, u32 qpn);
 void ipoib_reap_ah(struct work_struct *work);
 
+struct ipoib_path *__path_find(struct net_device *dev, void *gid);
 void ipoib_mark_paths_invalid(struct net_device *dev);
 void ipoib_flush_paths(struct net_device *dev);
 int ipoib_check_sm_sendonly_fullmember_support(struct ipoib_dev_priv *priv);

@@ -1318,6 +1318,8 @@ void ipoib_cm_destroy_tx(struct ipoib_cm
 	}
 }
 
+#define QPN_AND_OPTIONS_OFFSET	4
+
 static void ipoib_cm_tx_start(struct work_struct *work)
 {
 	struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,

@@ -1326,6 +1328,7 @@ static void ipoib_cm_tx_start(struct wor
 	struct ipoib_neigh *neigh;
 	struct ipoib_cm_tx *p;
 	unsigned long flags;
+	struct ipoib_path *path;
 	int ret;
 
 	struct ib_sa_path_rec pathrec;

@@ -1338,7 +1341,19 @@ static void ipoib_cm_tx_start(struct wor
 		p = list_entry(priv->cm.start_list.next, typeof(*p), list);
 		list_del_init(&p->list);
 		neigh = p->neigh;
+
 		qpn = IPOIB_QPN(neigh->daddr);
+		/*
+		 * As long as the search is with these 2 locks,
+		 * path existence indicates its validity.
+		 */
+		path = __path_find(dev, neigh->daddr + QPN_AND_OPTIONS_OFFSET);
+		if (!path) {
+			pr_info("%s ignore not valid path %pI6\n",
+				__func__,
+				neigh->daddr + QPN_AND_OPTIONS_OFFSET);
+			goto free_neigh;
+		}
 		memcpy(&pathrec, &p->path->pathrec, sizeof pathrec);
 
 		spin_unlock_irqrestore(&priv->lock, flags);

@@ -1350,6 +1365,7 @@ static void ipoib_cm_tx_start(struct wor
 		spin_lock_irqsave(&priv->lock, flags);
 
 		if (ret) {
+free_neigh:
 			neigh = p->neigh;
 			if (neigh) {
 				neigh->cm = NULL;

@@ -485,7 +485,7 @@ int ipoib_set_mode(struct net_device *de
 	return -EINVAL;
 }
 
-static struct ipoib_path *__path_find(struct net_device *dev, void *gid)
+struct ipoib_path *__path_find(struct net_device *dev, void *gid)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
 	struct rb_node *n = priv->path_tree.rb_node;

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/ib-ipoib-fix-memory-corruption-in-ipoib-cm-mode-connect-flow.patch queue-4.7/ib-core-fix-use-after-free-in-send_leave-function.patch