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From: Takashi Iwai <>
To: Greg Kroah-Hartman <>
Cc: Linyu Yuan <>,,
Subject: [REGRESSION 5.19] NULL dereference by ucsi_acpi driver
Date: Fri, 19 Aug 2022 18:32:43 +0200	[thread overview]
Message-ID: <> (raw)


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:

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

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)
-	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



             reply	other threads:[~2022-08-19 17:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-19 16:32 Takashi Iwai [this message]
2022-08-20 18:40 ` [REGRESSION 5.19] NULL dereference by ucsi_acpi driver Greg Kroah-Hartman
2022-08-22  2:44   ` Linyu Yuan
2022-08-30 12:51     ` Greg Kroah-Hartman
2022-08-30 12:53       ` Greg Kroah-Hartman
2022-08-22 13:24   ` Heikki Krogerus
2022-08-23  2:26     ` Linyu Yuan
2022-08-23  6:41       ` Greg Kroah-Hartman
2022-08-23  6:52         ` Takashi Iwai
2022-08-24  9:50 ` Thorsten Leemhuis

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