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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+icZUW=GTV0L884wdohaOdFmg4E4wdtSEOgF+KEGPcKzYOoow@mail.gmail.com>
Date:   Wed, 24 Feb 2021 19:08:59 +0100
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Sami Tolvanen <samitolvanen@...gle.com>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Gabriel Somlo <somlo@....edu>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Kees Cook <keescook@...omium.org>, qemu-devel@...gnu.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj_attribute

On Thu, Feb 11, 2021 at 9:41 PM 'Sami Tolvanen' via Clang Built Linux
<clang-built-linux@...glegroups.com> wrote:
>
> Hi Nathan,
>
> On Thu, Feb 11, 2021 at 11:43 AM Nathan Chancellor <nathan@...nel.org> 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
> >
> > $ dmesg | grep "CFI failure"
> > [   26.016832] CFI failure (target: fw_cfg_showrev+0x0/0x8):
> >
> > Fix this by converting fw_cfg_rev_attr to 'struct kobj_attribute' where
> > this would have been caught automatically by the incompatible pointer
> > types compiler warning. Update fw_cfg_showrev() accordingly.
> >
> > Fixes: 75f3e8e47f38 ("firmware: introduce sysfs driver for QEMU's fw_cfg device")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1299
> > Signed-off-by: Nathan Chancellor <nathan@...nel.org>
>
> Looks good to me. Thank you for sending the patch!
>
> Reviewed-by: Sami Tolvanen <samitolvanen@...gle.com>
>

Environment: Linux v5.11-10201-gc03c21ba6f4e plus Clang-CFI as of
24-Feb-2021 on top built with LLVM v13-git.

Tested-by: Sedat Dilek <sedat.dilek@...il.com>

- Sedat -