Re: [linux-next:master 3857/7963] arch/x86/crypto/sm4-aesni-avx-asm_64.o: warning: objtool: sm4_aesni_avx_crypt8()+0x8: sibling call from callable instruction with modified stack frame

[Peter Zijlstra]

On Mon, Sep 20, 2021 at 10:56:56AM -0700, Josh Poimboeuf wrote:
> From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Subject: [PATCH] x86/crypto/sm4: Fix frame pointer stack corruption
> 
> sm4_aesni_avx_crypt8() sets up the frame pointer (which includes pushing
> RBP) before doing a conditional sibling call to sm4_aesni_avx_crypt4(),
> which sets up an additional frame pointer.  Things will not go well when
> sm4_aesni_avx_crypt4() pops only the innermost single frame pointer and
> then tries to return to the outermost frame pointer.
> 
> Sibling calls need to occur with an empty stack frame.  Do the
> conditional sibling call *before* setting up the stack pointer.
> 
> This fixes the following warning:
> 
>   arch/x86/crypto/sm4-aesni-avx-asm_64.o: warning: objtool: sm4_aesni_avx_crypt8()+0x8: sibling call from callable instruction with modified stack frame
> 
> Fixes: a7ee22ee1445 ("crypto: x86/sm4 - add AES-NI/AVX/x86_64 implementation")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Arnd Bergmann <arnd@xxxxxxxxxx>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

> ---
>  arch/x86/crypto/sm4-aesni-avx-asm_64.S | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/crypto/sm4-aesni-avx-asm_64.S b/arch/x86/crypto/sm4-aesni-avx-asm_64.S
> index fa2c3f50aecb..a50df13de222 100644
> --- a/arch/x86/crypto/sm4-aesni-avx-asm_64.S
> +++ b/arch/x86/crypto/sm4-aesni-avx-asm_64.S
> @@ -367,10 +367,12 @@ SYM_FUNC_START(sm4_aesni_avx_crypt8)
>  	 *	%rdx: src (1..8 blocks)
>  	 *	%rcx: num blocks (1..8)
>  	 */
> -	FRAME_BEGIN
>  
>  	cmpq $5, %rcx;
>  	jb sm4_aesni_avx_crypt4;
> +
> +	FRAME_BEGIN
> +
>  	vmovdqu (0 * 16)(%rdx), RA0;
>  	vmovdqu (1 * 16)(%rdx), RA1;
>  	vmovdqu (2 * 16)(%rdx), RA2;
> -- 
> 2.31.1
>