[PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Eugeniu Rosca]

Address below Coverity complaint (Feb 25, 2020, 8:06 AM CET):

*** CID 1458999:  Error handling issues  (CHECKED_RETURN)
/drivers/usb/core/hub.c: 1869 in hub_probe()
1863
1864            if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
1865                    hub->quirk_check_port_auto_suspend = 1;
1866
1867            if (id->driver_info & HUB_QUIRK_DISABLE_AUTOSUSPEND) {
1868                    hub->quirk_disable_autosuspend = 1;
 >>>     CID 1458999:  Error handling issues  (CHECKED_RETURN)
 >>>     Calling "usb_autopm_get_interface" without checking return value (as is done elsewhere 97 out of 111 times).
1869                    usb_autopm_get_interface(intf);
1870            }
1871
1872            if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)
1873                    return 0;
1874

Fixes: 1208f9e1d758c9 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub")
Cc: Hardik Gajjar <hgajjar@de.adit-jv.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: scan-admin@coverity.com
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---
 drivers/usb/core/hub.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 1d212f82c69b..ff04ca28970d 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1865,8 +1865,12 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 		hub->quirk_check_port_auto_suspend = 1;
 
 	if (id->driver_info & HUB_QUIRK_DISABLE_AUTOSUSPEND) {
-		hub->quirk_disable_autosuspend = 1;
-		usb_autopm_get_interface(intf);
+		int r = usb_autopm_get_interface(intf);
+
+		if (!r)
+			hub->quirk_disable_autosuspend = 1;
+		else
+			dev_dbg(&intf->dev, "disable autosuspend err=%d\n", r);
 	}
 
 	if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)
-- 
2.25.0

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Alan Stern]

On Tue, 25 Feb 2020, Eugeniu Rosca wrote:

> Address below Coverity complaint (Feb 25, 2020, 8:06 AM CET):
> 
> *** CID 1458999:  Error handling issues  (CHECKED_RETURN)
> /drivers/usb/core/hub.c: 1869 in hub_probe()
> 1863
> 1864            if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
> 1865                    hub->quirk_check_port_auto_suspend = 1;
> 1866
> 1867            if (id->driver_info & HUB_QUIRK_DISABLE_AUTOSUSPEND) {
> 1868                    hub->quirk_disable_autosuspend = 1;
>  >>>     CID 1458999:  Error handling issues  (CHECKED_RETURN)
>  >>>     Calling "usb_autopm_get_interface" without checking return value (as is done elsewhere 97 out of 111 times).
> 1869                    usb_autopm_get_interface(intf);
> 1870            }
> 1871
> 1872            if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)
> 1873                    return 0;
> 1874
> 
> Fixes: 1208f9e1d758c9 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub")
> Cc: Hardik Gajjar <hgajjar@de.adit-jv.com>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reported-by: scan-admin@coverity.com
> Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
> ---
>  drivers/usb/core/hub.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 1d212f82c69b..ff04ca28970d 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1865,8 +1865,12 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  		hub->quirk_check_port_auto_suspend = 1;
>  
>  	if (id->driver_info & HUB_QUIRK_DISABLE_AUTOSUSPEND) {
> -		hub->quirk_disable_autosuspend = 1;
> -		usb_autopm_get_interface(intf);
> +		int r = usb_autopm_get_interface(intf);
> +
> +		if (!r)
> +			hub->quirk_disable_autosuspend = 1;
> +		else
> +			dev_dbg(&intf->dev, "disable autosuspend err=%d\n", r);
>  	}
>  
>  	if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)

This change is not necessary, because the resume operation cannot fail
at this point (interfaces are always powered-up during probe).  A
better solution would be to call usb_autpm_get_interface_no_resume()
instead.

On the other hand, the other places that call
usb_autopm_get_interface() without checking should be audited.  Some of
them almost certainly need to be fixed.

Alan Stern

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Eugeniu Rosca]

Hi Alan,

Many thanks for the prompt review.

On Tue, Feb 25, 2020 at 10:32:32AM -0500, Alan Stern wrote:
> On Tue, 25 Feb 2020, Eugeniu Rosca wrote:
> > +		int r = usb_autopm_get_interface(intf);
> > +
> > +		if (!r)
> > +			hub->quirk_disable_autosuspend = 1;
> > +		else
> > +			dev_dbg(&intf->dev, "disable autosuspend err=%d\n", r);
> >  	}
> >  
> >  	if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)
> 
> This change is not necessary, because the resume operation cannot fail
> at this point (interfaces are always powered-up during probe).

Agreed to avoid unneeded complexity.

> A better solution would be to call usb_autpm_get_interface_no_resume()
> instead.

Pushed to https://lore.kernel.org/lkml/20200225183057.31953-1-erosca@de.adit-jv.com

> 
> On the other hand, the other places that call
> usb_autopm_get_interface() without checking should be audited.  Some of
> them almost certainly need to be fixed.

A quick 'git grep' outputs below list of auditable candidates [1].

With no relevant devices at hand, I would avoid touching these drivers,
since oftentimes even legitimate patches introduce regressions w/o
testing.

If anybody volunteers with testing, I guess it should be quick to
either convert usb_autpm_get_interface to *_no_resume variant or
handle the return value in place in below instances.

[1] (v5.6-rc3) git grep -En "[^=]\s+usb_autopm_get_interface\("
  drivers/input/touchscreen/usbtouchscreen.c:1788:  usb_autopm_get_interface(intf);
  drivers/media/usb/stkwebcam/stk-webcam.c:628:     usb_autopm_get_interface(dev->interface);
  drivers/net/usb/hso.c:1308:                       usb_autopm_get_interface(serial->parent->interface);
  drivers/net/usb/r8152.c:5231:                     usb_autopm_get_interface(tp->intf);
  sound/usb/usx2y/us122l.c:192:                     usb_autopm_get_interface(iface);

-- 
Best Regards
Eugeniu Rosca

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Alan Stern]

On Tue, 25 Feb 2020, Eugeniu Rosca wrote:

> Hi Alan,
> 
> Many thanks for the prompt review.
> 
> On Tue, Feb 25, 2020 at 10:32:32AM -0500, Alan Stern wrote:
> > On Tue, 25 Feb 2020, Eugeniu Rosca wrote:
> > > +		int r = usb_autopm_get_interface(intf);
> > > +
> > > +		if (!r)
> > > +			hub->quirk_disable_autosuspend = 1;
> > > +		else
> > > +			dev_dbg(&intf->dev, "disable autosuspend err=%d\n", r);
> > >  	}
> > >  
> > >  	if (hub_configure(hub, &desc->endpoint[0].desc) >= 0)
> > 
> > This change is not necessary, because the resume operation cannot fail
> > at this point (interfaces are always powered-up during probe).
> 
> Agreed to avoid unneeded complexity.
> 
> > A better solution would be to call usb_autpm_get_interface_no_resume()
> > instead.
> 
> Pushed to https://lore.kernel.org/lkml/20200225183057.31953-1-erosca@de.adit-jv.com
> 
> > 
> > On the other hand, the other places that call
> > usb_autopm_get_interface() without checking should be audited.  Some of
> > them almost certainly need to be fixed.
> 
> A quick 'git grep' outputs below list of auditable candidates [1].
> 
> With no relevant devices at hand, I would avoid touching these drivers,
> since oftentimes even legitimate patches introduce regressions w/o
> testing.
> 
> If anybody volunteers with testing, I guess it should be quick to
> either convert usb_autpm_get_interface to *_no_resume variant or
> handle the return value in place in below instances.
> 
> [1] (v5.6-rc3) git grep -En "[^=]\s+usb_autopm_get_interface\("
>   drivers/input/touchscreen/usbtouchscreen.c:1788:  usb_autopm_get_interface(intf);
>   drivers/media/usb/stkwebcam/stk-webcam.c:628:     usb_autopm_get_interface(dev->interface);
>   drivers/net/usb/hso.c:1308:                       usb_autopm_get_interface(serial->parent->interface);
>   drivers/net/usb/r8152.c:5231:                     usb_autopm_get_interface(tp->intf);
>   sound/usb/usx2y/us122l.c:192:                     usb_autopm_get_interface(iface);

Your regular expression isn't right because it doesn't match lines
where the usb_autopm_get_interface() is preceded only by one whitespace
character (i.e., a tab).  It also will match lines where there are two
space characters between the = sign and the function name.  I think
what you want is more like "(^|[^=[:space:]])\s*" at the start of the
RE.

A revised search finds line 997 in drivers/usb/core/hub.c and lines
216, 269 in drivers/usb/core/port.c.  (I didn't try looking in any
other directories.)  AFAICT all three of these should check the return
value, although a error message in the kernel log probably isn't
needed.

Do you want to fix those instances up also, maybe merging them in with
the existing patch?

Alan Stern

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Eugeniu Rosca]

Hi Alan,

On Tue, Feb 25, 2020 at 02:39:23PM -0500, Alan Stern wrote:
> On Tue, 25 Feb 2020, Eugeniu Rosca wrote:
> > [1] (v5.6-rc3) git grep -En "[^=]\s+usb_autopm_get_interface\("
> >   drivers/input/touchscreen/usbtouchscreen.c:1788:  usb_autopm_get_interface(intf);
> >   drivers/media/usb/stkwebcam/stk-webcam.c:628:     usb_autopm_get_interface(dev->interface);
> >   drivers/net/usb/hso.c:1308:                       usb_autopm_get_interface(serial->parent->interface);
> >   drivers/net/usb/r8152.c:5231:                     usb_autopm_get_interface(tp->intf);
> >   sound/usb/usx2y/us122l.c:192:                     usb_autopm_get_interface(iface);
> 
> Your regular expression isn't right because it doesn't match lines
> where the usb_autopm_get_interface() is preceded only by one whitespace
> character (i.e., a tab).  It also will match lines where there are two
> space characters between the = sign and the function name.  I think
> what you want is more like "(^|[^=[:space:]])\s*" at the start of the
> RE.

Agreed. My version filters out some true positives.

> 
> A revised search finds line 997 in drivers/usb/core/hub.c and lines
> 216, 269 in drivers/usb/core/port.c.  (I didn't try looking in any
> other directories.)  AFAICT all three of these should check the return
> value, although a error message in the kernel log probably isn't
> needed.
> 
> Do you want to fix those instances up also, maybe merging them in with
> the existing patch?

I wonder if squashing all these fixes into one patch is the best option.

There are three commits fixed by the proposed changes in usb core:
 - v5.6-rc3 commit 1208f9e1d758c9 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub")
 - v3.9-rc1 commit 971fcd492cebf5 ("usb: add runtime pm support for usb port device")
 - v2.6.33-rc1 commit 253e05724f9230 ("USB: add a "remove hardware" sysfs attribute")

I assume a single fix will create some pain when applying it to the
stable branches. Do you have any preference/inputs about that?

-- 
Best Regards
Eugeniu Rosca

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Alan Stern]

On Tue, 25 Feb 2020, Eugeniu Rosca wrote:

> Hi Alan,
> 
> On Tue, Feb 25, 2020 at 02:39:23PM -0500, Alan Stern wrote:
> > On Tue, 25 Feb 2020, Eugeniu Rosca wrote:
> > > [1] (v5.6-rc3) git grep -En "[^=]\s+usb_autopm_get_interface\("
> > >   drivers/input/touchscreen/usbtouchscreen.c:1788:  usb_autopm_get_interface(intf);
> > >   drivers/media/usb/stkwebcam/stk-webcam.c:628:     usb_autopm_get_interface(dev->interface);
> > >   drivers/net/usb/hso.c:1308:                       usb_autopm_get_interface(serial->parent->interface);
> > >   drivers/net/usb/r8152.c:5231:                     usb_autopm_get_interface(tp->intf);
> > >   sound/usb/usx2y/us122l.c:192:                     usb_autopm_get_interface(iface);
> > 
> > Your regular expression isn't right because it doesn't match lines
> > where the usb_autopm_get_interface() is preceded only by one whitespace
> > character (i.e., a tab).  It also will match lines where there are two
> > space characters between the = sign and the function name.  I think
> > what you want is more like "(^|[^=[:space:]])\s*" at the start of the
> > RE.
> 
> Agreed. My version filters out some true positives.
> 
> > 
> > A revised search finds line 997 in drivers/usb/core/hub.c and lines
> > 216, 269 in drivers/usb/core/port.c.  (I didn't try looking in any
> > other directories.)  AFAICT all three of these should check the return
> > value, although a error message in the kernel log probably isn't
> > needed.
> > 
> > Do you want to fix those instances up also, maybe merging them in with
> > the existing patch?
> 
> I wonder if squashing all these fixes into one patch is the best option.
> 
> There are three commits fixed by the proposed changes in usb core:
>  - v5.6-rc3 commit 1208f9e1d758c9 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub")
>  - v3.9-rc1 commit 971fcd492cebf5 ("usb: add runtime pm support for usb port device")
>  - v2.6.33-rc1 commit 253e05724f9230 ("USB: add a "remove hardware" sysfs attribute")
> 
> I assume a single fix will create some pain when applying it to the
> stable branches. Do you have any preference/inputs about that?

If you prefer to split this up into multiple patches, that's fine with 
me.

Alan Stern

Re: [PATCH] usb: hub: Fix unhandled return value of usb_autopm_get_interface()

[Eugeniu Rosca]

Hi Alan,

On Tue, Feb 25, 2020 at 03:54:20PM -0500, Alan Stern wrote:
> On Tue, 25 Feb 2020, Eugeniu Rosca wrote:
> > There are three commits fixed by the proposed changes in usb core:
> >  - v5.6-rc3 commit 1208f9e1d758c9 ("USB: hub: Fix the broken detection of USB3 device in SMSC hub")
> >  - v3.9-rc1 commit 971fcd492cebf5 ("usb: add runtime pm support for usb port device")
> >  - v2.6.33-rc1 commit 253e05724f9230 ("USB: add a "remove hardware" sysfs attribute")
> > 
> > I assume a single fix will create some pain when applying it to the
> > stable branches. Do you have any preference/inputs about that?
> 
> If you prefer to split this up into multiple patches, that's fine with 
> me.

Please, check https://lore.kernel.org/lkml/20200226175036.14946-1-erosca@de.adit-jv.com/

-- 
Best Regards
Eugeniu Rosca