Re: [PATCH 04/11] hso: fix memory leak in hso_create_rfkill()

From: Dan Williams
Date: Tue Jan 20 2015 - 13:41:47 EST


On Tue, 2015-01-20 at 14:13 +0100, Oliver Neukum wrote:
> On Tue, 2015-01-20 at 13:29 +0100, Olivier Sobrie wrote:
> > When the rfkill interface was created, a buffer containing the name
> > of the rfkill node was allocated. This buffer was never freed when the
> > device disappears.
> >
> > To fix the problem, we put the name given to rfkill_alloc() in
> > the hso_net structure.
> >
> > Signed-off-by: Olivier Sobrie <olivier@xxxxxxxxx>
> > ---
> > drivers/net/usb/hso.c | 12 +++---------
> > 1 file changed, 3 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
> > index 470ef9e..a49ac2e 100644
> > --- a/drivers/net/usb/hso.c
> > +++ b/drivers/net/usb/hso.c
> > @@ -153,6 +153,7 @@ struct hso_net {
> > struct hso_device *parent;
> > struct net_device *net;
> > struct rfkill *rfkill;
> > + char name[8];
> >
> > struct usb_endpoint_descriptor *in_endp;
> > struct usb_endpoint_descriptor *out_endp;
> > @@ -2467,27 +2468,20 @@ static void hso_create_rfkill(struct hso_device *hso_dev,
> > {
> > struct hso_net *hso_net = dev2net(hso_dev);
> > struct device *dev = &hso_net->net->dev;
> > - char *rfkn;
> >
> > - rfkn = kzalloc(20, GFP_KERNEL);
> > - if (!rfkn)
> > - dev_err(dev, "%s - Out of memory\n", __func__);
> > -
> > - snprintf(rfkn, 20, "hso-%d",
> > + snprintf(hso_net->name, sizeof(hso_net->name), "hso-%d",
> > interface->altsetting->desc.bInterfaceNumber);
>
> That number is not unique. Indeed it will be identical for all devices.

I would say just do "static u32 rfkill_counter = 0" and

+ snprintf(hso_net->name, sizeof(hso_net->name), "hso-%d",
+ rfkill_counter++);

We can't just use the netdev's name because that may have conflicts.
eg, the netdev will get hso0 when plugged in (and thus rfkill would get
hso-0) but then udev will rename that to something like wwp0s26f7u2i8.
Then the second HSO you plug in will get the name 'hso0', and so the
second rfkill would get 'hso-0', but that's already taken by the first
rfkill... Which is why I just suggest a counter.

Dan

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