From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Takashi Iwai <tiwai@suse.de>
Cc: Linyu Yuan <quic_linyyuan@quicinc.com>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [REGRESSION 5.19] NULL dereference by ucsi_acpi driver
Date: Sat, 20 Aug 2022 20:40:52 +0200 [thread overview]
Message-ID: <YwEqtGB2WldUeiEN@kroah.com> (raw)
In-Reply-To: <87r11cmbx0.wl-tiwai@suse.de>
On Fri, Aug 19, 2022 at 06:32:43PM +0200, Takashi Iwai wrote:
> 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()
Adding Heikki to the thread...
>
> 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'll be glad to revert this now, unless Heikki thinks:
>
> 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.
that is any better?
thanks,
greg k-h
next prev parent reply other threads:[~2022-08-21 7:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 16:32 [REGRESSION 5.19] NULL dereference by ucsi_acpi driver Takashi Iwai
2022-08-20 18:40 ` Greg Kroah-Hartman [this message]
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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