linux-kernel - Re: [PATCH 0/2] firewire: obsolete cast of function callback toward CFI

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Date:   Fri, 22 May 2020 19:35:49 +0200
From:   Oscar Carter <oscar.carter@....com>
To:     Takashi Sakamoto <o-takashi@...amocchi.jp>, keescook@...omium.org,
        mchehab@...nel.org, clemens@...isch.de, tiwai@...e.de,
        perex@...ex.cz
Cc:     Oscar Carter <oscar.carter@....com>,
        kernel-hardening@...ts.openwall.com,
        linux1394-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        levonshe@...il.com, alsa-devel@...a-project.org,
        stefanr@...6.in-berlin.de
Subject: Re: [PATCH 0/2] firewire: obsolete cast of function callback toward
 CFI

Hi,

On Wed, May 20, 2020 at 03:47:24PM +0900, Takashi Sakamoto wrote:
> Hi,
>
> Oscar Carter works for Control Flow Integrity build. Any cast
> of function callback is inconvenient for the work. Unfortunately,
> current code of firewire-core driver includes the cast[1] and Oscar
> posted some patches to remove it[2]. The patch is itself good. However,
> it includes changes existent kernel API and all of drivers as user
> of the API get affects from the change.
>
> This patchset is an alternative idea to add a new kernel API specific
> for multichannel isoc context. The existent kernel API and drivers is
> left as is.
>
> Practically, no in-kernel drivers use the additional API. Although the
> API is exported in the patchset, it's better to discuss about unexporting
> the API.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firewire/core-cdev.c#n985
> [2] https://lore.kernel.org/lkml/20200519173425.4724-1-oscar.carter@gmx.com/
>
> Regards
>
> Takashi Sakamoto (2):
>   firewire-core: add kernel API to construct multichannel isoc context
>   firewire-core: obsolete cast of function callback
>
>  drivers/firewire/core-cdev.c | 44 +++++++++++++++++++-----------------
>  drivers/firewire/core-iso.c  | 17 ++++++++++++++
>  include/linux/firewire.h     |  3 +++
>  3 files changed, 43 insertions(+), 21 deletions(-)
>
> --
> 2.25.1
>
Thanks for your work and new proposal. I've done a test build an it cleans the
-Wcast-function-type warning without the need to change the current API. So, it
looks good to me.

Thanks,
Oscar Carter