mailbox: tegra-hsp: Use after free in tegra_hsp_remove_doorbells()

We have to use the _safe version of list_for_each() because we're
freeing the pointer as we go along.  (This might not show up testing
depending on what config options you have enabled).

Fixes: 0fe88461a0ec ("mailbox: Add Tegra HSP driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/mailbox/tegra-hsp.c

@@ -334,12 +334,12 @@ static struct mbox_chan *of_tegra_hsp_xlate(struct mbox_controller *mbox,
 
 static void tegra_hsp_remove_doorbells(struct tegra_hsp *hsp)
 {
-	struct tegra_hsp_doorbell *db;
+	struct tegra_hsp_doorbell *db, *tmp;
 	unsigned long flags;
 
 	spin_lock_irqsave(&hsp->lock, flags);
 
-	list_for_each_entry(db, &hsp->doorbells, list)
+	list_for_each_entry_safe(db, tmp, &hsp->doorbells, list)
 		__tegra_hsp_doorbell_destroy(db);
 
 	spin_unlock_irqrestore(&hsp->lock, flags);