RE: [PATCH v2] usb: typec: hd3ss3220: Fix NULL pointer crash

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Hi Heikki,

> Subject: Re: [PATCH v2] usb: typec: hd3ss3220: Fix NULL pointer crash
> 
> Hi Biju,
> 
> On Fri, Dec 09, 2022 at 05:07:40PM +0000, Biju Das wrote:
> > The value returned by usb_role_switch_get() can be NULL and it leads
> > to NULL pointer crash. This patch fixes this issue by adding NULL
> > check for the role switch handle.
> >
> > [   25.336613] Hardware name: Silicon Linux RZ/G2E evaluation kit EK874
> (CAT874 + CAT875) (DT)
> > [   25.344991] Workqueue: events_unbound deferred_probe_work_func
> > [   25.350869] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS
> BTYPE=--)
> > [   25.357854] pc : renesas_usb3_role_switch_get+0x40/0x80
> [renesas_usb3]
> > [   25.364428] lr : renesas_usb3_role_switch_get+0x24/0x80
> [renesas_usb3]
> > [   25.370986] sp : ffff80000a4b3a40
> > [   25.374311] x29: ffff80000a4b3a40 x28: 0000000000000000 x27:
> 0000000000000000
> > [   25.381476] x26: ffff80000a3ade78 x25: ffff00000a809005 x24:
> ffff80000117f178
> > [   25.388641] x23: ffff00000a8d7810 x22: ffff00000a8d8410 x21:
> 0000000000000000
> > [   25.395805] x20: ffff000011cd7080 x19: ffff000011cd7080 x18:
> 0000000000000020
> > [   25.402969] x17: ffff800076196000 x16: ffff800008004000 x15:
> 0000000000004000
> > [   25.410133] x14: 000000000000022b x13: 0000000000000001 x12:
> 0000000000000001
> > [   25.417291] x11: 0000000000000000 x10: 0000000000000a40 x9 :
> ffff80000a4b3770
> > [   25.424452] x8 : ffff00007fbc9000 x7 : 0040000000000008 x6 :
> ffff00000a8d8590
> > [   25.431615] x5 : ffff80000a4b3960 x4 : 0000000000000000 x3 :
> ffff00000a8d84f4
> > [   25.438776] x2 : 0000000000000218 x1 : ffff80000a715218 x0 :
> 0000000000000218
> > [   25.445942] Call trace:
> > [   25.448398]  renesas_usb3_role_switch_get+0x40/0x80 [renesas_usb3]
> > [   25.454613]  renesas_usb3_role_switch_set+0x4c/0x440 [renesas_usb3]
> > [   25.460908]  usb_role_switch_set_role+0x44/0xa4
> > [   25.465468]  hd3ss3220_set_role+0xa0/0x100 [hd3ss3220]
> > [   25.470635]  hd3ss3220_probe+0x118/0x2fc [hd3ss3220]
> > [   25.475621]  i2c_device_probe+0x338/0x384
> 
> Based on that backtrace, your role switch is not NULL.
> 
> You can only end up calling renesas_usb3_role_switch_set() if your
> hd3ss3220->role_sw contains a handle to the renesas usb3 role switch.

Looks you are correct.

> 
> > Fixes: 5a9a8a4c5058 ("usb: typec: hd3ss3220: hd3ss3220_probe() warn:
> > passing zero to 'PTR_ERR'")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > ---
> > This issue triggered on RZ/G2E board, where there is no USB3 firmware
> > and it returned a null role switch handle.
> >
> > v1->v2:
> >  * Make it as individual patch
> >  * Added Cc tag
> > ---
> >  drivers/usb/typec/hd3ss3220.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/hd3ss3220.c
> > b/drivers/usb/typec/hd3ss3220.c index 2a58185fb14c..c24bbccd14f9
> > 100644
> > --- a/drivers/usb/typec/hd3ss3220.c
> > +++ b/drivers/usb/typec/hd3ss3220.c
> > @@ -186,7 +186,10 @@ static int hd3ss3220_probe(struct i2c_client
> *client,
> >  		hd3ss3220->role_sw = usb_role_switch_get(hd3ss3220->dev);
> >  	}
> >
> > -	if (IS_ERR(hd3ss3220->role_sw)) {
> > +	if (!hd3ss3220->role_sw) {
> > +		ret = -ENODEV;
> > +		goto err_put_fwnode;
> > +	} else if (IS_ERR(hd3ss3220->role_sw)) {
> >  		ret = PTR_ERR(hd3ss3220->role_sw);
> >  		goto err_put_fwnode;
> >  	}
> 
> You should not do that.
> 
> Either I'm missing something, or this patch is hiding some other issue.

Looks It is a bug in renesas_usb3.c rather than this driver.

But how we will prevent hd3ss3220_set_role being called after
usb_role_switch_unregister(usb3->role_sw) from renesas_usb3.c
driver??

Cheers,
Biju




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