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Date:   Thu, 25 Mar 2021 21:35:01 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Peter Zijlstra <peterz@infradead.org>, bpf@vger.kernel.org,
        linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 06/17] kthread: use WARN_ON_FUNCTION_MISMATCH
Message-ID: <202103252134.BCC32ECC9@keescook>
References: <20210323203946.2159693-1-samitolvanen@google.com>
 <20210323203946.2159693-7-samitolvanen@google.com>
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On Tue, Mar 23, 2021 at 01:39:35PM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, a callback function passed to
> __kthread_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 != ktead_delayed_work_timer_fn);
> 
> Use WARN_ON_FUNCTION_MISMATCH() instead to disable the warning
> when CFI and modules are both enabled.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

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

-- 
Kees Cook