On Wed, May 20, 2020 at 10:24 PM Kees Cook <keesc...@chromium.org> wrote:
>
> On Wed, May 20, 2020 at 06:52:21PM -0500, Li Yang wrote:
> > On Mon, May 18, 2020 at 5:57 PM Kees Cook <keesc...@chromium.org> wrote:
> > > Hm, looking at this code, I see a few other things that need to be
> > > fixed:
> > >
> > > 1) drivers/tty/serial/ucc_uart.c does not do a be32_to_cpu() conversion
> > > on the length test (understandably, a little-endian system has never
> > > run
> > > this code since it's ppc specific), but it's still wrong:
> > >
> > > if (firmware->header.length != fw->size) {
> > >
> > > compare to the firmware loader:
> > >
> > > length = be32_to_cpu(hdr->length);
> > >
> > > 2) drivers/soc/fsl/qe/qe.c does not perform bounds checking on the
> > > per-microcode offsets, so the uploader might send data outside the
> > > firmware buffer. Perhaps:
> >
> > We do validate the CRC for each microcode, it is unlikely the CRC
> > check can pass if the offset or length is not correct. But you are
> > probably right that it will be safer to check the boundary and fail
>
> Right, but a malicious firmware file could still match CRC but trick the
> kernel code.
>
> > quicker before we actually start the CRC check. Will you come up with
> > a formal patch or you want us to deal with it?
>
> It sounds like Gustavo will be sending one, though I don't think either
> of us have the hardware to test it with, so if you could do that part,
> that would be great! :)
That will be great. I think Zhao Qiang can help with the testing part.
Regards,
Leo
