Re: Updating cypress/brcm firmware in linux-firmware for CVE-2019-15126

[Hans de Goede]

Hi,

On 3/5/20 4:50 AM, Chi-Hsien Lin wrote:
> (+Chris)
>
> On 03/04/2020 7:45, Hans de Goede wrote:
> > Hi,
> >
> > On 2/26/20 11:16 PM, Hans de Goede wrote:
> > > Hello Cypress people,
> > >
> > > Can we please get updated firmware for
> > > brcm/brcmfmac4356-pcie.bin and brcm/brcmfmac4356-sdio.bin
> > > fixing CVE-2019-15126 as well as for any other affected
> > > models (the 4356 is explicitly named in the CVE description) ?
> > >
> > > The current Cypress firmware files in linux-firmware are
> > > quite old, e.g. for brcm/brcmfmac4356-pcie.bin linux-firmware has:
> > > version 7.35.180.176 dated 2017-10-23, way before the CVE
> > >
> > > Where as https://community.cypress.com/docs/DOC-19000 /
> > > cypress-fmac-v4.14.77-2020_0115.zip has:
> > > version 7.35.180.197 which presumably contains a fix (no changelog)
> >
> > Ping?
> >
> > The very old age of the firmware files in linux-firmware is really
> > UNACCEPTABLE and very irresponsible from a security POV. Please
> > fix this very soon.
> >
> > If you do not reply to this email I see no choice but to switch
> > the firmwares in linux-firmware over to the ones from the SDK which
> > you do regularly update, e.g. those from:
> > https://community.cypress.com/docs/DOC-19000
> >
> > Yes those are under an older, slightly different version of the Cypress
> > license, which is less then ideal, but that license is still acceptable
> > for linux-firmware (*) and since you are not providing any updates to
> > the special builds you have been doing for linux-firmware you are
> > really leaving us no option other then switching to the SDK version
> > of the firmwares.
>
> Hans,
>
> As we discussed previously, those files are not suitable for linux-firmware for the reason of regulatory (blobs are only for Cypress reference boards and could violate regulatory on other boards);

But the special builds you are doing for Linux firmware have a clm_blob
too, the only difference is that it is embedded. If it is possible to
embed a generic version of the clm_blob, then why not provide separate
a generic version of the separate clm_blob files, so that those can be
used together with build which you release regularly as part of your
SDK ?

This way you do not need to do special builds for linux-firmware,
which seems to be the main bottleneck for having up2date Cypress
firmware files inside linux-firmware.

> also clm_blob download is not supported in kernels prior to 4.15 so those files won't work with older kernels.

That is a valid concern, I'm not sure what the rules for linux-firmware
are with regards to this. OTOH those are quite old kernels and if we
must choice between having recent firmware for modern kernels or old
kernel compatibility I guess the preference would be to have recent
firmware. Likely devices using such old kernels are not updating their
version of linux-firmware anyways.

> Chris owns the Cypress firmware upstream strategy and will explain our going-forward strategy to you.

Ok.

Regards,

Hans