linux-kernel - [PATCH] x86/mce/dev-mcelog: Fix "make W=1" warning about strncpy

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Date:   Wed, 27 May 2020 11:28:08 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Tony Luck <tony.luck@...el.com>, kbuild test robot <lkp@...el.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] x86/mce/dev-mcelog: Fix "make W=1" warning about strncpy

The kbuild test robot reported this warning:

arch/x86/kernel/cpu/mce/dev-mcelog.c: In function 'dev_mcelog_init_device':
arch/x86/kernel/cpu/mce/dev-mcelog.c:346:2: warning: 'strncpy' output truncated before terminating nul copying 12 bytes from a string of the same length [-Wstringop-truncation]

This is accurate, but I don't care that the trailing NUL character isn't copied.
The string being copied is just a magic number signature so that crash dump
tools can be sure they are decoding the right blob of memory.

Change to use memcpy() instead of strncpy()

Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/mce/dev-mcelog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/dev-mcelog.c b/arch/x86/kernel/cpu/mce/dev-mcelog.c
index d089567a9ce8..bcb379b2fd42 100644
--- a/arch/x86/kernel/cpu/mce/dev-mcelog.c
+++ b/arch/x86/kernel/cpu/mce/dev-mcelog.c
@@ -343,7 +343,7 @@ static __init int dev_mcelog_init_device(void)
 	if (!mcelog)
 		return -ENOMEM;
 
-	strncpy(mcelog->signature, MCE_LOG_SIGNATURE, sizeof(mcelog->signature));
+	memcpy(mcelog->signature, MCE_LOG_SIGNATURE, sizeof(mcelog->signature));
 	mcelog->len = mce_log_len;
 	mcelog->recordlen = sizeof(struct mce);
 
-- 
2.21.1