linux-kernel - Re: [PATCH v3 09/17] treewide: Change list

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Message-ID: <202103252135.9B17EFB@keescook>
Date:   Thu, 25 Mar 2021 21:35:24 -0700
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>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Peter Zijlstra <peterz@...radead.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 v3 09/17] treewide: Change list_sort to use const pointers

On Tue, Mar 23, 2021 at 01:39:38PM -0700, Sami Tolvanen wrote:
> list_sort() internally casts the comparison function passed to it
> to a different type with constant struct list_head pointers, and
> uses this pointer to call the functions, which trips indirect call
> Control-Flow Integrity (CFI) checking.
> 
> Instead of removing the consts, this change defines the
> list_cmp_func_t type and changes the comparison function types of
> all list_sort() callers to use const pointers, thus avoiding type
> mismatches.
> 
> Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>

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

-- 
Kees Cook