linux-kernel - [PATCH 5.7 367/477] x86/mce/dev-mcelog: Fix -Wstringop-truncation warning about strncpy()

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Date:   Tue, 23 Jun 2020 21:56:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kbuild test robot <lkp@...el.com>,
        Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 367/477] x86/mce/dev-mcelog: Fix -Wstringop-truncation warning about strncpy()

From: Tony Luck <tony.luck@...el.com>

[ Upstream commit 7ccddc4613db446dc3cbb69a3763ba60ec651d13 ]

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.

Use memcpy() instead of strncpy().

Fixes: d8ecca4043f2 ("x86/mce/dev-mcelog: Dynamically allocate space for machine check records")
Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20200527182808.27737-1-tony.luck@intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 d089567a9ce82..bcb379b2fd42e 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);
 
-- 
2.25.1