[PATCH 3.2 38/60] IB/cm: Fix rb-tree duplicate free and use-after-free

[Ben Hutchings]

3.2.73-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Doron Tsur <doront@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
Signed-off-by: Matan Barak <matanb@xxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -856,6 +856,11 @@ 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:
 		ib_cancel_mad(cm_id_priv->av.port->mad_agent, cm_id_priv->msg);
@@ -3092,7 +3097,10 @@ 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;
 

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