rpmsg: glink: Don't send pending rx_done during remove

Attempting to transmit rx_done messages after the GLINK instance is
being torn down will cause use after free and memory leaks. So cancel
the intent_work and free up the pending intents.

With this there are no concurrent accessors of the channel left during
qcom_glink_native_remove() and there is therefor no need to hold the
spinlock during this operation - which would prohibit the use of
cancel_work_sync() in the release function. So remove this.

Fixes: 1d2ea36e ("rpmsg: glink: Add rx done command")
Cc: stable@vger.kernel.org
Acked-by: Chris Lew <clew@codeaurora.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/rpmsg/qcom_glink_native.c

@@ -241,11 +241,23 @@ static void qcom_glink_channel_release(struct kref *ref)
 {
 	struct glink_channel *channel = container_of(ref, struct glink_channel,
 						     refcount);
+	struct glink_core_rx_intent *intent;
 	struct glink_core_rx_intent *tmp;
 	unsigned long flags;
 	int iid;
 
+	/* cancel pending rx_done work */
+	cancel_work_sync(&channel->intent_work);
+
 	spin_lock_irqsave(&channel->intent_lock, flags);
+	/* Free all non-reuse intents pending rx_done work */
+	list_for_each_entry_safe(intent, tmp, &channel->done_intents, node) {
+		if (!intent->reuse) {
+			kfree(intent->data);
+			kfree(intent);
+		}
+	}
+
 	idr_for_each_entry(&channel->liids, tmp, iid) {
 		kfree(tmp->data);
 		kfree(tmp);
@@ -1625,7 +1637,6 @@ void qcom_glink_native_remove(struct qcom_glink *glink)
 	struct glink_channel *channel;
 	int cid;
 	int ret;
-	unsigned long flags;
 
 	disable_irq(glink->irq);
 	cancel_work_sync(&glink->rx_work);
@@ -1634,7 +1645,6 @@ void qcom_glink_native_remove(struct qcom_glink *glink)
 	if (ret)
 		dev_warn(glink->dev, "Can't remove GLINK devices: %d\n", ret);
 
-	spin_lock_irqsave(&glink->idr_lock, flags);
 	/* Release any defunct local channels, waiting for close-ack */
 	idr_for_each_entry(&glink->lcids, channel, cid)
 		kref_put(&channel->refcount, qcom_glink_channel_release);
@@ -1645,7 +1655,6 @@ void qcom_glink_native_remove(struct qcom_glink *glink)
 
 	idr_destroy(&glink->lcids);
 	idr_destroy(&glink->rcids);
-	spin_unlock_irqrestore(&glink->idr_lock, flags);
 	mbox_free_channel(glink->mbox_chan);
 }
 EXPORT_SYMBOL_GPL(qcom_glink_native_remove);