linux-kernel - [PATCH] driver: soc: xilinx: use _safe loop iterator to avoid a use after free

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Date:   Fri, 21 Apr 2023 13:44:54 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Abhyuday Godhasara <abhyuday.godhasara@...inx.com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        Rajan Vaja <rajan.vaja@...inx.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tejas Patel <tejas.patel@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] 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: c7fdb2404f66 ("drivers: soc: xilinx: add xilinx event management driver")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
Found by static analysis and not tested.

 drivers/soc/xilinx/xlnx_event_manager.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/xilinx/xlnx_event_manager.c b/drivers/soc/xilinx/xlnx_event_manager.c
index c76381899ef4..f9d9b82b562d 100644
--- a/drivers/soc/xilinx/xlnx_event_manager.c
+++ b/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) {
-- 
2.39.2