Messages in this thread Patch in this message | | | Date | Fri, 19 Aug 2022 18:32:43 +0200 | From | Takashi Iwai <> | Subject | [REGRESSION 5.19] NULL dereference by ucsi_acpi driver |
| |
Hi,
we've got multiple reports about 5.19 kernel starting crashing after some time, and this turned out to be triggered by ucsi_acpi driver. The details are found in: https://bugzilla.suse.com/show_bug.cgi?id=1202386
The culprit seems to be the commit 87d0e2f41b8c usb: typec: ucsi: add a common function ucsi_unregister_connectors()
This commit looks as if it were a harmless cleanup, but this failed in a subtle way. Namely, in the error scenario, the driver gets an error at ucsi_register_altmodes(), and goes to the error handling to release the resources. Through this refactoring, the release part was unified to a funciton ucsi_unregister_connectors(). And there, it has a NULL check of con->wq, and it bails out the loop if it's NULL. Meanwhile, ucsi_register_port() itself still calls destroy_workqueue() and clear con->wq at its error path. This ended up in the leftover power supply device with the uninitialized / cleared device.
It was confirmed that the problem could be avoided by a simple revert.
I guess another fix could be removing the part clearing con->wq, i.e.
--- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1192,11 +1192,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int index) out_unlock: mutex_unlock(&con->lock); - if (ret && con->wq) { - destroy_workqueue(con->wq); - con->wq = NULL; - } - return ret; } ... but it's totally untested and I'm not entirely sure whether it's better.
thanks,
Takashi
| |