linux-kernel - Re: [PATCH] qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj

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Date:   Fri, 2 Apr 2021 11:31:10 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Sedat Dilek <sedat.dilek@...il.com>, Gabriel Somlo <somlo@....edu>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        qemu-devel@...gnu.org,
        Clang-Built-Linux ML <clang-built-linux@...glegroups.com>,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: Re: [PATCH] qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj_attribute

On Fri, Apr 02, 2021 at 11:25:42AM -0700, Kees Cook wrote:
> On Fri, Apr 02, 2021 at 08:42:07AM +0200, Sedat Dilek wrote:
> > On Thu, Feb 25, 2021 at 10:25 PM Kees Cook <keescook@...omium.org> wrote:
> > >
> > > On Thu, 11 Feb 2021 12:42:58 -0700, Nathan Chancellor wrote:
> > > > fw_cfg_showrev() is called by an indirect call in kobj_attr_show(),
> > > > which violates clang's CFI checking because fw_cfg_showrev()'s second
> > > > parameter is 'struct attribute', whereas the ->show() member of 'struct
> > > > kobj_structure' expects the second parameter to be of type 'struct
> > > > kobj_attribute'.
> > > >
> > > > $ cat /sys/firmware/qemu_fw_cfg/rev
> > > > 3
> > > >
> > > > [...]
> > >
> > > Applied to kspp/cfi/cleanups, thanks!
> > >
> > > [1/1] qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj_attribute
> > >       https://git.kernel.org/kees/c/f5c4679d6c49
> > >
> > 
> > I have queued this up in my custom patchset
> > (for-5.12/kspp-cfi-cleanups-20210225).
> > 
> > What is the plan to get this upstream?
> 
> I haven't sent it to Linus yet -- I was expecting to batch more of these
> and send them for v5.13. (But if the kvm folks snag it, that's good
> too.)

I am going to be putting the CFI series through its paces on both arm64
and x86_64 over the next week or so on several different machines (in
fact, I am writing up a report right now) so I will probably have some
more of these as I find them.

Cheers,
Nathan