Re: [PATCH v2] thunderbolt: Fix to check return value of ida_simple_get

[Mukesh Ojha]

On 3/21/2019 11:19 AM, Mika Westerberg wrote:
> On Thu, Mar 21, 2019 at 02:09:41AM +0530, Mukesh Ojha wrote:
> > On 3/20/2019 9:59 PM, Mika Westerberg wrote:
> > > On Wed, Mar 20, 2019 at 11:24:45AM -0500, Aditya Pakki wrote:
> > > > In enumerate_services, ida_simple_get on failure can return an error and
> > > > leaks memory during device_register failure. The patch ensures that
> > > > the dev_set_name is set on non failure cases, and releases memory in
> > > > case of failure.
> > > >
> > > > Signed-off-by: Aditya Pakki <pakki001@xxxxxxx>
> > > >
> > > > ---
> > > > v1: Missed cleanup of svc in case of allocation failure and
> > > > device_register failure.
> > > > ---
> > > >    drivers/thunderbolt/xdomain.c | 9 ++++++++-
> > > >    1 file changed, 8 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/thunderbolt/xdomain.c b/drivers/thunderbolt/xdomain.c
> > > > index e27dd8beb94b..eb08275185bf 100644
> > > > --- a/drivers/thunderbolt/xdomain.c
> > > > +++ b/drivers/thunderbolt/xdomain.c
> > > > @@ -740,6 +740,7 @@ static void enumerate_services(struct tb_xdomain *xd)
> > > >    	struct tb_service *svc;
> > > >    	struct tb_property *p;
> > > >    	struct device *dev;
> > > > +	int id;
> > > >    	/*
> > > >    	 * First remove all services that are not available anymore in
> > > > @@ -768,7 +769,12 @@ static void enumerate_services(struct tb_xdomain *xd)
> > > >    			break;
> > > >    		}
> > > > -		svc->id = ida_simple_get(&xd->service_ids, 0, 0, GFP_KERNEL);
> > > > +		id = ida_simple_get(&xd->service_ids, 0, 0, GFP_KERNEL);
> > > > +		if (id < 0) {
> > > > +			kfree(svc);
> > > > +			break;
> > > > +		}
> > > > +		svc->id = id;
> > > >    		svc->dev.bus = &tb_bus_type;
> > > >    		svc->dev.type = &tb_service_type;
> > > >    		svc->dev.parent = &xd->dev;
> > > > @@ -776,6 +782,7 @@ static void enumerate_services(struct tb_xdomain *xd)
> > > >    		if (device_register(&svc->dev)) {
> > > >    			put_device(&svc->dev);
> > > > +			kfree(svc);
> > > You can't do this after device_register() is called. The put_device()
> > > above is sufficient.
> >
> > If device_register fails, how would svc gets freed? we need to kfree svc
> > here as well.
> Please read the comment on top of device_register(). It should explain.
>
> So no kfree here.

Thanks for pointer Mika.

Overlooked the fact that dev is a data member of svc not a pointer, also 
noticed there are many places in tree where , it is not
followed.

Thanks,
Mukesh