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Date:   Fri, 18 Nov 2022 12:10:26 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     x86@kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-crypto@vger.kernel.org
Subject: Re: [PATCH v2 08/12] crypto: x86/sm4 - fix crash with CFI enabled
Message-ID: <Y3fmskgfAb/xxzpS@sol.localdomain>
References: <20221118194421.160414-1-ebiggers@kernel.org>
 <20221118194421.160414-9-ebiggers@kernel.org>
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On Fri, Nov 18, 2022 at 11:44:17AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> sm4_aesni_avx_ctr_enc_blk8(), sm4_aesni_avx_cbc_dec_blk8(),
> sm4_aesni_avx_cfb_dec_blk8(), sm4_aesni_avx2_ctr_enc_blk16(),
> sm4_aesni_avx2_cbc_dec_blk16(), and sm4_aesni_avx2_cfb_dec_blk16() are
> called via indirect function calls.  Therefore they need to use
> SYM_TYPED_FUNC_START instead of SYM_FUNC_START to cause their type
> hashes to be emitted when the kernel is built with CONFIG_CFI_CLANG=y.
> Otherwise, the code crashes with a CFI failure.
> 
> (Or at least that should be the case.  For some reason the CFI checks in
> sm4_avx_cbc_decrypt(), sm4_avx_cfb_decrypt(), and sm4_avx_ctr_crypt()
> are not always being generated, using current tip-of-tree clang.
> Anyway, this patch is a good idea anyway.)

Sami, is it expected that a CFI check isn't being generated for the indirect
call to 'func' in sm4_avx_cbc_decrypt()?  I'm using LLVM commit 4a7be42d922af0.

- Eric