Re: [PATCH] USB: gadget: Fix the memory leak in raw_gadget driver

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Jul 21, 2023 at 01:56:35PM +0800, Z qiang wrote:
> >
> > On Fri, Jul 14, 2023 at 9:40 AM Zqiang <qiang.zhang1211@gmail.com> wrote:
> > >
> > > Currently, increasing raw_dev->count happens before invoke the
> > > raw_queue_event(), if the raw_queue_event() return error, invoke
> > > raw_release() will not trigger the dev_free() to be called.
> > >
> > > [  268.905865][ T5067] raw-gadget.0 gadget.0: failed to queue event
> > > [  268.912053][ T5067] udc dummy_udc.0: failed to start USB Raw Gadget: -12
> > > [  268.918885][ T5067] raw-gadget.0: probe of gadget.0 failed with error -12
> > > [  268.925956][ T5067] UDC core: USB Raw Gadget: couldn't find an available UDC or it's busy
> > > [  268.934657][ T5067] misc raw-gadget: fail, usb_gadget_register_driver returned -16
> > >
> > > BUG: memory leak
> > >
> > > [<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
> > > [<ffffffff8347eb55>] kmalloc include/linux/slab.h:582 [inline]
> > > [<ffffffff8347eb55>] kzalloc include/linux/slab.h:703 [inline]
> > > [<ffffffff8347eb55>] dev_new drivers/usb/gadget/legacy/raw_gadget.c:191 [inline]
> > > [<ffffffff8347eb55>] raw_open+0x45/0x110 drivers/usb/gadget/legacy/raw_gadget.c:385
> > > [<ffffffff827d1d09>] misc_open+0x1a9/0x1f0 drivers/char/misc.c:165
> > >
> > > [<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
> > > [<ffffffff8347cd2f>] kmalloc include/linux/slab.h:582 [inline]
> > > [<ffffffff8347cd2f>] raw_ioctl_init+0xdf/0x410 drivers/usb/gadget/legacy/raw_gadget.c:460
> > > [<ffffffff8347dfe9>] raw_ioctl+0x5f9/0x1120 drivers/usb/gadget/legacy/raw_gadget.c:1250
> > > [<ffffffff81685173>] vfs_ioctl fs/ioctl.c:51 [inline]
> > >
> > > [<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
> > > [<ffffffff833ecc6a>] kmalloc include/linux/slab.h:582 [inline]
> > > [<ffffffff833ecc6a>] kzalloc include/linux/slab.h:703 [inline]
> > > [<ffffffff833ecc6a>] dummy_alloc_request+0x5a/0xe0 drivers/usb/gadget/udc/dummy_hcd.c:665
> > > [<ffffffff833e9132>] usb_ep_alloc_request+0x22/0xd0 drivers/usb/gadget/udc/core.c:196
> > > [<ffffffff8347f13d>] gadget_bind+0x6d/0x370 drivers/usb/gadget/legacy/raw_gadget.c:292
> > >
> > > This commit therefore invoke kref_get() under the condition that
> > > raw_queue_event() return success.
> > >
> > > Reported-by: syzbot+feb045d335c1fdde5bf7@syzkaller.appspotmail.com
> > > Closes: https://syzkaller.appspot.com/bug?extid=feb045d335c1fdde5bf7
> > > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
> > > ---
> > >  drivers/usb/gadget/legacy/raw_gadget.c | 10 ++++++----
> > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c
> > > index 2acece16b890..e549022642e5 100644
> > > --- a/drivers/usb/gadget/legacy/raw_gadget.c
> > > +++ b/drivers/usb/gadget/legacy/raw_gadget.c
> > > @@ -310,13 +310,15 @@ static int gadget_bind(struct usb_gadget *gadget,
> > >         dev->eps_num = i;
> > >         spin_unlock_irqrestore(&dev->lock, flags);
> > >
> > > -       /* Matches kref_put() in gadget_unbind(). */
> > > -       kref_get(&dev->count);
> > > -
> > >         ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
> > > -       if (ret < 0)
> > > +       if (ret < 0) {
> > >                 dev_err(&gadget->dev, "failed to queue event\n");
> > > +               set_gadget_data(gadget, NULL);
> > > +               return ret;
> > > +       }
> > >
> > > +       /* Matches kref_put() in gadget_unbind(). */
> > > +       kref_get(&dev->count);
> > >         return ret;
> > >  }
> > >
> > > --
> > > 2.17.1
> >
> > Indeed, if gadget_bind fails due to a raw_queue_event failure, the
> > core gadget code will never call gadget_unbind.
> >
> > Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
> > Tested-by: Andrey Konovalov <andreyknvl@gmail.com>
> >
> 
> Hi Greg
> 
> Friendly ping :)

$ mdfrm -c ~/mail/todo/
1685 messages in /home/gregkh/mail/todo/

For various reasons I am way behind in getting to review public patches
like these, sorry.  Give me a chance to catch up, should be through them
all by the end of next week.

In the meantime, to help reduce my load, you can always help review
other patches that have been sent to the list for review.

thanks,

greg k-h