Patch "IB/cm: Fix rb-tree duplicate free and use-after-free" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

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

    IB/cm: Fix rb-tree duplicate free and use-after-free

to the 4.2-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-cm-fix-rb-tree-duplicate-free-and-use-after-free.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0ca81a2840f77855bbad1b9f172c545c4dc9e6a4 Mon Sep 17 00:00:00 2001
From: Doron Tsur <doront@mellanox.com>
Date: Sun, 11 Oct 2015 15:58:17 +0300
Subject: IB/cm: Fix rb-tree duplicate free and use-after-free

From: Doron Tsur <doront@mellanox.com>

commit 0ca81a2840f77855bbad1b9f172c545c4dc9e6a4 upstream.

ib_send_cm_sidr_rep could sometimes erase the node from the sidr
(depending on errors in the process). Since ib_send_cm_sidr_rep is
called both from cm_sidr_req_handler and cm_destroy_id, cm_id_priv
could be either erased from the rb_tree twice or not erased at all.
Fixing that by making sure it's erased only once before freeing
cm_id_priv.

Fixes: a977049dacde ('[PATCH] IB: Add the kernel CM implementation')
Signed-off-by: Doron Tsur <doront@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/infiniband/core/cm.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -873,6 +873,11 @@ retest:
 	case IB_CM_SIDR_REQ_RCVD:
 		spin_unlock_irq(&cm_id_priv->lock);
 		cm_reject_sidr_req(cm_id_priv, IB_SIDR_REJECT);
+		spin_lock_irq(&cm.lock);
+		if (!RB_EMPTY_NODE(&cm_id_priv->sidr_id_node))
+			rb_erase(&cm_id_priv->sidr_id_node,
+				 &cm.remote_sidr_table);
+		spin_unlock_irq(&cm.lock);
 		break;
 	case IB_CM_REQ_SENT:
 	case IB_CM_MRA_REQ_RCVD:
@@ -3112,7 +3117,10 @@ int ib_send_cm_sidr_rep(struct ib_cm_id
 	spin_unlock_irqrestore(&cm_id_priv->lock, flags);
 
 	spin_lock_irqsave(&cm.lock, flags);
-	rb_erase(&cm_id_priv->sidr_id_node, &cm.remote_sidr_table);
+	if (!RB_EMPTY_NODE(&cm_id_priv->sidr_id_node)) {
+		rb_erase(&cm_id_priv->sidr_id_node, &cm.remote_sidr_table);
+		RB_CLEAR_NODE(&cm_id_priv->sidr_id_node);
+	}
 	spin_unlock_irqrestore(&cm.lock, flags);
 	return 0;
 


Patches currently in stable-queue which might be from doront@mellanox.com are

queue-4.2/ib-cm-fix-rb-tree-duplicate-free-and-use-after-free.patch