linux-kernel - Re: [PATCH AUTOSEL 5.10 30/34] hinic: Replace memcpy() with direct assignment

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Message-ID: <20220629130201.GB13395@duo.ucw.cz>
Date:   Wed, 29 Jun 2022 15:02:01 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, llvm@...ts.linux.dev,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net,
        edumazet@...gle.com, pabeni@...hat.com, jiri@...dia.com,
        leon@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.10 30/34] hinic: Replace memcpy() with direct
 assignment

Hi!

> From: Kees Cook <keescook@...omium.org>
> 
> [ Upstream commit 1e70212e031528918066a631c9fdccda93a1ffaa ]
> 
> Under CONFIG_FORTIFY_SOURCE=y and CONFIG_UBSAN_BOUNDS=y, Clang is bugged
> here for calculating the size of the destination buffer (0x10 instead of
> 0x14). This copy is a fixed size (sizeof(struct fw_section_info_st)), with
> the source and dest being struct fw_section_info_st, so the memcpy should
> be safe, assuming the index is within bounds, which is UBSAN_BOUNDS's
> responsibility to figure out.
> 
> Avoid the whole thing and just do a direct assignment. This results in
> no change to the executable code.

This is just a workaround for Clang bug uncovered by 281d0c962752
("fortify: Add Clang support"), and we don't have that in 5.10-stable.

Please drop.

Best regards,
								Pavel
> +++ b/drivers/net/ethernet/huawei/hinic/hinic_devlink.c
> @@ -43,9 +43,7 @@ static bool check_image_valid(struct hinic_devlink_priv *priv, const u8 *buf,
>  
>  	for (i = 0; i < fw_image->fw_info.fw_section_cnt; i++) {
>  		len += fw_image->fw_section_info[i].fw_section_len;
> -		memcpy(&host_image->image_section_info[i],
> -		       &fw_image->fw_section_info[i],
> -		       sizeof(struct fw_section_info_st));
> +		host_image->image_section_info[i] = fw_image->fw_section_info[i];
>  	}
>  
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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