linux-hardening - Re: [PATCH 05/17] workqueue: cfi: disable callback pointer check with modules

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Message-ID: <202103111840.58C5D95F@keescook>
Date:   Thu, 11 Mar 2021 18:43:18 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Sami Tolvanen <samitolvanen@...gle.com>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Will Deacon <will@...nel.org>, Jessica Yu <jeyu@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Tejun Heo <tj@...nel.org>,
        bpf@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kbuild@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/17] workqueue: cfi: disable callback pointer check
 with modules

On Thu, Mar 11, 2021 at 04:49:07PM -0800, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, a callback function passed to
> __queue_delayed_work from a module points to a jump table entry
> defined in the module instead of the one used in the core kernel,
> which breaks function address equality in this check:
> 
>   WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
> 
> Disable the warning when CFI and modules are enabled.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook