linux-kernel - [PATCH] hinic: Replace memcpy() with direct assignment

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Message-Id: <20220616052312.292861-1-keescook@chromium.org>
Date:   Wed, 15 Jun 2022 22:23:12 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Kees Cook <keescook@...omium.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, Leon Romanovsky <leon@...nel.org>,
        Jiri Pirko <jiri@...dia.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Simon Horman <simon.horman@...igine.com>,
        netdev@...r.kernel.org, llvm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] hinic: Replace memcpy() with direct assignment

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.

Cc: "David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: Nathan Chancellor <nathan@...nel.org>
Cc: Nick Desaulniers <ndesaulniers@...gle.com>
Cc: Tom Rix <trix@...hat.com>
Cc: Leon Romanovsky <leon@...nel.org>
Cc: Jiri Pirko <jiri@...dia.com>
Cc: Vladimir Oltean <olteanv@...il.com>
Cc: Simon Horman <simon.horman@...igine.com>
Cc: netdev@...r.kernel.org
Cc: llvm@...ts.linux.dev
Link: https://github.com/ClangBuiltLinux/linux/issues/1592
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/ethernet/huawei/hinic/hinic_devlink.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/huawei/hinic/hinic_devlink.c b/drivers/net/ethernet/huawei/hinic/hinic_devlink.c
index 60ae8bfc5f69..1749d26f4bef 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_devlink.c
+++ 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];
 	}
 
 	if (len != fw_image->fw_len ||
-- 
2.32.0