linux-kernel - Re: [PATCH] PCI/pwrctrl: Cancel outstanding rescan work when unregistering

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Message-ID: <20250423174429.GA441684@bhelgaas>
Date: Wed, 23 Apr 2025 12:44:29 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Brian Norris <briannorris@...omium.org>
Cc: Bartosz Golaszewski <brgl@...ev.pl>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Brian Norris <briannorris@...gle.com>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH] PCI/pwrctrl: Cancel outstanding rescan work when
 unregistering

On Wed, Apr 09, 2025 at 11:53:13AM -0700, Brian Norris wrote:
> From: Brian Norris <briannorris@...gle.com>
> 
> It's possible to trigger use-after-free here by:
> (a) forcing rescan_work_func() to take a long time and
> (b) utilizing a pwrctrl driver that may be unloaded for some reason.
> 
> I'm unlucky to trigger both of these in development. It's likely much
> more difficult to hit this in practice.
> 
> Anyway, we should ensure our work is finished before we allow our data
> structures to be cleaned up.
> 
> Fixes: 8f62819aaace ("PCI/pwrctl: Rescan bus on a separate thread")
> Cc: Konrad Dybcio <konradybcio@...nel.org>
> Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> Signed-off-by: Brian Norris <briannorris@...gle.com>
> Signed-off-by: Brian Norris <briannorris@...omium.org>

Looking for ack/reviewed-by from Bartosz before doing anything here.

> ---
> 
>  drivers/pci/pwrctrl/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
> index 9cc7e2b7f2b5..6bdbfed584d6 100644
> --- a/drivers/pci/pwrctrl/core.c
> +++ b/drivers/pci/pwrctrl/core.c
> @@ -101,6 +101,8 @@ EXPORT_SYMBOL_GPL(pci_pwrctrl_device_set_ready);
>   */
>  void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl)
>  {
> +	cancel_work_sync(&pwrctrl->work);
> +
>  	/*
>  	 * We don't have to delete the link here. Typically, this function
>  	 * is only called when the power control device is being detached. If
> -- 
> 2.49.0.604.gff1f9ca942-goog
>