[PATCH] usb/c67x00/c67x00-drv: Fix Data Race bug

[PATCH] usb/c67x00/c67x00-drv: Fix Data Race bug

[madhuparnabhowmik10]

From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

Currently in c67x00_drv_probe() IRQ is requested before calling
c67x00_probe_sie() and hence if interrupt happens the reading of certain
variables in the handler can race with initialization of the variables,
for e.g. sie->sie_num is written in c67x00_probe_sie() and read in
 c67x00_hcd_irq().
Hence, this patch calls c67x00_probe_sie() before requesting IRQ in
probe.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
---
 drivers/usb/c67x00/c67x00-drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/c67x00/c67x00-drv.c b/drivers/usb/c67x00/c67x00-drv.c
index 53838e7d4eef..2e816d5ca0eb 100644
--- a/drivers/usb/c67x00/c67x00-drv.c
+++ b/drivers/usb/c67x00/c67x00-drv.c
@@ -146,6 +146,9 @@ static int c67x00_drv_probe(struct platform_device *pdev)
 	c67x00_ll_init(c67x00);
 	c67x00_ll_hpi_reg_init(c67x00);
 
+	for (i = 0; i < C67X00_SIES; i++)
+		c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
+
 	ret = request_irq(res2->start, c67x00_irq, 0, pdev->name, c67x00);
 	if (ret) {
 		dev_err(&pdev->dev, "Cannot claim IRQ\n");
@@ -158,9 +161,6 @@ static int c67x00_drv_probe(struct platform_device *pdev)
 		goto reset_failed;
 	}
 
-	for (i = 0; i < C67X00_SIES; i++)
-		c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
-
 	platform_set_drvdata(pdev, c67x00);
 
 	return 0;
-- 
2.17.1

Re: [PATCH] usb/c67x00/c67x00-drv: Fix Data Race bug

[Greg KH]

On Wed, Aug 26, 2020 at 08:14:59PM +0530, madhuparnabhowmik10@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> 
> Currently in c67x00_drv_probe() IRQ is requested before calling
> c67x00_probe_sie() and hence if interrupt happens the reading of certain
> variables in the handler can race with initialization of the variables,
> for e.g. sie->sie_num is written in c67x00_probe_sie() and read in
>  c67x00_hcd_irq().
> Hence, this patch calls c67x00_probe_sie() before requesting IRQ in
> probe.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> ---
>  drivers/usb/c67x00/c67x00-drv.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/c67x00/c67x00-drv.c b/drivers/usb/c67x00/c67x00-drv.c
> index 53838e7d4eef..2e816d5ca0eb 100644
> --- a/drivers/usb/c67x00/c67x00-drv.c
> +++ b/drivers/usb/c67x00/c67x00-drv.c
> @@ -146,6 +146,9 @@ static int c67x00_drv_probe(struct platform_device *pdev)
>  	c67x00_ll_init(c67x00);
>  	c67x00_ll_hpi_reg_init(c67x00);
>  
> +	for (i = 0; i < C67X00_SIES; i++)
> +		c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
> +
>  	ret = request_irq(res2->start, c67x00_irq, 0, pdev->name, c67x00);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Cannot claim IRQ\n");
> @@ -158,9 +161,6 @@ static int c67x00_drv_probe(struct platform_device *pdev)
>  		goto reset_failed;
>  	}
>  
> -	for (i = 0; i < C67X00_SIES; i++)
> -		c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
> -
>  	platform_set_drvdata(pdev, c67x00);
>  
>  	return 0;

Have you tested this on hardware to verify it works properly?

thanks,

greg k-h

Re: [PATCH] usb/c67x00/c67x00-drv: Fix Data Race bug

[Madhuparna Bhowmik]

On Fri, Aug 28, 2020 at 1:10 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Wed, Aug 26, 2020 at 08:14:59PM +0530, madhuparnabhowmik10@gmail.com wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> >
> > Currently in c67x00_drv_probe() IRQ is requested before calling
> > c67x00_probe_sie() and hence if interrupt happens the reading of certain
> > variables in the handler can race with initialization of the variables,
> > for e.g. sie->sie_num is written in c67x00_probe_sie() and read in
> >  c67x00_hcd_irq().
> > Hence, this patch calls c67x00_probe_sie() before requesting IRQ in
> > probe.
> >
> > Found by Linux Driver Verification project (linuxtesting.org).
> >
> > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> > ---
> >  drivers/usb/c67x00/c67x00-drv.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/c67x00/c67x00-drv.c b/drivers/usb/c67x00/c67x00-drv.c
> > index 53838e7d4eef..2e816d5ca0eb 100644
> > --- a/drivers/usb/c67x00/c67x00-drv.c
> > +++ b/drivers/usb/c67x00/c67x00-drv.c
> > @@ -146,6 +146,9 @@ static int c67x00_drv_probe(struct platform_device *pdev)
> >       c67x00_ll_init(c67x00);
> >       c67x00_ll_hpi_reg_init(c67x00);
> >
> > +     for (i = 0; i < C67X00_SIES; i++)
> > +             c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
> > +
> >       ret = request_irq(res2->start, c67x00_irq, 0, pdev->name, c67x00);
> >       if (ret) {
> >               dev_err(&pdev->dev, "Cannot claim IRQ\n");
> > @@ -158,9 +161,6 @@ static int c67x00_drv_probe(struct platform_device *pdev)
> >               goto reset_failed;
> >       }
> >
> > -     for (i = 0; i < C67X00_SIES; i++)
> > -             c67x00_probe_sie(&c67x00->sie[i], c67x00, i);
> > -
> >       platform_set_drvdata(pdev, c67x00);
> >
> >       return 0;
>
> Have you tested this on hardware to verify it works properly?

No, I haven't, don't think I have the relevant hardware.
It would be great if someone could test this and add a Tested-by tag.

Thanks,
Madhuparna

>
> thanks,
>
> greg k-h