driver: soc: xilinx: use _safe loop iterator to avoid a use after free

The hash_for_each_possible() loop dereferences "eve_data" to get the
next item on the list.  However the loop frees eve_data so it leads to
a use after free.  Use hash_for_each_possible_safe() instead.

Fixes: c7fdb24 ("drivers: soc: xilinx: add xilinx event management driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/761e0e4a-4caf-4a71-8f47-1c6ad908a848@kili.mountain
Signed-off-by: Michal Simek <michal.simek@amd.com>

Author: Dan Carpenter

drivers/soc/xilinx/xlnx_event_manager.c

@@ -192,11 +192,12 @@ static int xlnx_remove_cb_for_suspend(event_cb_func_t cb_fun)
 	struct registered_event_data *eve_data;
 	struct agent_cb *cb_pos;
 	struct agent_cb *cb_next;
+	struct hlist_node *tmp;
 
 	is_need_to_unregister = false;
 
 	/* Check for existing entry in hash table for given cb_type */
-	hash_for_each_possible(reg_driver_map, eve_data, hentry, PM_INIT_SUSPEND_CB) {
+	hash_for_each_possible_safe(reg_driver_map, eve_data, tmp, hentry, PM_INIT_SUSPEND_CB) {
 		if (eve_data->cb_type == PM_INIT_SUSPEND_CB) {
 			/* Delete the list of callback */
 			list_for_each_entry_safe(cb_pos, cb_next, &eve_data->cb_list_head, list) {
@@ -228,11 +229,12 @@ static int xlnx_remove_cb_for_notify_event(const u32 node_id, const u32 event,
 	u64 key = ((u64)node_id << 32U) | (u64)event;
 	struct agent_cb *cb_pos;
 	struct agent_cb *cb_next;
+	struct hlist_node *tmp;
 
 	is_need_to_unregister = false;
 
 	/* Check for existing entry in hash table for given key id */
-	hash_for_each_possible(reg_driver_map, eve_data, hentry, key) {
+	hash_for_each_possible_safe(reg_driver_map, eve_data, tmp, hentry, key) {
 		if (eve_data->key == key) {
 			/* Delete the list of callback */
 			list_for_each_entry_safe(cb_pos, cb_next, &eve_data->cb_list_head, list) {