Em Tue, 3 Jul 2018 21:07:07 +0900
Akihiro TSUKADA <tskd08@xxxxxxxxx> escreveu:
> Hi,
> thanks for the report.
>
> > 47 buf = NULL;
> >
> > Condition rlen > 0, taking false branch.
> >
> > 48 if (rlen > 0) {
> > 49 buf = kmalloc(rlen, GFP_KERNEL);
> > 50 if (!buf)
> > 51 return -ENOMEM;
> > 52 }
> >
> > 53 usleep_range(1000, 2000); /* avoid I2C errors */
> > 54
> > CID 1470241 (#1 of 1): Explicit null dereferenced (FORWARD_NULL).
> > var_deref_model: Passing null pointer buf to usb_control_msg, which
> > dereferences it.
> >
> > 55 ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0),
> > req, type,
> > 56 value, index, buf, rlen, 2000);
> >
> >
> > The assignment of buf = NULL means a null buffer is passed down the usb
> > control message stack until it eventually gets dereferenced. This only
> > occurs when rlen <= 0. I was unsure how to fix this for the case when
> > rlen <= 0, so I am flagging this up as an issue that needs fixing.
> >
>
> Since rlen is an u16, null pointer is passed only when rlen == 0,
> so I think it is not a problem,
> but I am OK to add a guard in order to make scan result clean.
There was another patch proposed to fix this issue with does the
right thing when rlen == 0. I rebased it on the top of the current
tree:
https://git.linuxtv.org/media_tree.git/commit/?id=0b666e1c8120c0b17a8a68aaed58e22011f06ab3
That should cover both cases.
Thanks,
Mauro
