In gb_interface_create, &intf->mode_switch_completion is bound with gb_interface_mode_switch_work. Then it will be started by gb_interface_request_mode_switch. Here is the relevant code. if (!queue_work(system_long_wq, &intf->mode_switch_work)) { ... }
If we call gb_interface_release to make cleanup, there may be an unfinished work. This function will call kfree to free the object "intf". However, if gb_interface_mode_switch_work is scheduled to run after kfree, it may cause use-after-free error as gb_interface_mode_switch_work will use the object "intf". The possible execution flow that may lead to the issue is as follows:
CPU0 CPU1
| gb_interface_create | gb_interface_request_mode_switch gb_interface_release | kfree(intf) (free) | | gb_interface_mode_switch_work | mutex_lock(&intf->mutex) (use)
Fix it by canceling the work before kfree.
Signed-off-by: Sicong Huang congei42@163.com --- drivers/greybus/interface.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/greybus/interface.c b/drivers/greybus/interface.c index fd58a86b0888..d022bfb5e95d 100644 --- a/drivers/greybus/interface.c +++ b/drivers/greybus/interface.c @@ -693,6 +693,7 @@ static void gb_interface_release(struct device *dev)
trace_gb_interface_release(intf);
+ cancel_work_sync(&intf->mode_switch_work); kfree(intf); }