Re: [PATCH -next] bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()

[Manivannan Sadhasivam <mani@kernel.org>]

On Fri, May 21, 2021 at 05:47:44PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Apr 13, 2021 at 04:03:18PM +0000, Wei Yongjun wrote:
> > This driver's remove path calls del_timer(). However, that function
> > does not wait until the timer handler finishes. This means that the
> > timer handler may still be running after the driver's remove function
> > has finished, which would result in a use-after-free.
> > 
> > Fix by calling del_timer_sync(), which makes sure the timer handler
> > has finished, and unable to re-schedule itself.
> > 
> > Fixes: 8562d4fe34a3 ("mhi: pci_generic: Add health-check")
> > Reported-by: Hulk Robot <hulkci@huawei.com>
> > Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> Loic, could you please review this patch as well?
> 

Nvm, Loic did review the patch.

Thanks,
Mani

> Thanks,
> Mani
> 
> > ---
> >  drivers/bus/mhi/pci_generic.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> > index 7c810f02a2ef..5b19e877d17a 100644
> > --- a/drivers/bus/mhi/pci_generic.c
> > +++ b/drivers/bus/mhi/pci_generic.c
> > @@ -708,7 +708,7 @@ static void mhi_pci_remove(struct pci_dev *pdev)
> >  	struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
> >  	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> >  
> > -	del_timer(&mhi_pdev->health_check_timer);
> > +	del_timer_sync(&mhi_pdev->health_check_timer);
> >  	cancel_work_sync(&mhi_pdev->recovery_work);
> >  
> >  	if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
> >