linux-hardening - Re: [PATCH 10/17] lkdtm: use __va

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Message-ID: <202103111845.1D52CBC1@keescook>
Date:   Thu, 11 Mar 2021 18:45:43 -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 10/17] lkdtm: use __va_function

On Thu, Mar 11, 2021 at 04:49:12PM -0800, Sami Tolvanen wrote:
> To ensure we take the actual address of a function in kernel text, use
> __va_function. Otherwise, with CONFIG_CFI_CLANG, the compiler replaces
> the address with a pointer to the CFI jump table, which is actually in
> the module when compiled with CONFIG_LKDTM=m.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>

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

-- 
Kees Cook