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

[Michal Simek <michal.simek@xxxxxxx>]

On 4/21/23 12:44, Dan Carpenter wrote:
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>
>
> 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@xxxxxxxxxx>
> ---
> 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

Applied.
M