linux-kernel - [tip:x86/mm] x86/mtrr: Convert to use strncpy_from

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Message-ID: <tip-7f8ec5a4f01aa7d03e94a3d99d7b5f9c02d7fe5a@git.kernel.org>
Date:   Wed, 16 May 2018 03:34:24 -0700
From:   tip-bot for Andy Shevchenko <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, brgerst@...il.com,
        linux-kernel@...r.kernel.org, dvlasenk@...hat.com, mcgrof@...e.com,
        mingo@...nel.org, tglx@...utronix.de, bp@...en8.de,
        jpoimboe@...hat.com, andriy.shevchenko@...ux.intel.com,
        torvalds@...ux-foundation.org, luto@...nel.org, toshi.kani@...com,
        hpa@...or.com, akpm@...ux-foundation.org
Subject: [tip:x86/mm] x86/mtrr: Convert to use strncpy_from_user() helper

Commit-ID:  7f8ec5a4f01aa7d03e94a3d99d7b5f9c02d7fe5a
Gitweb:     https://git.kernel.org/tip/7f8ec5a4f01aa7d03e94a3d99d7b5f9c02d7fe5a
Author:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
AuthorDate: Tue, 15 May 2018 21:05:35 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 16 May 2018 09:47:23 +0200

x86/mtrr: Convert to use strncpy_from_user() helper

Replace the open coded string fetch from user-space with strncpy_from_user().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Toshi Kani <toshi.kani@...com>
Link: http://lkml.kernel.org/r/20180515180535.89703-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/mtrr/if.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c
index 42b4f2f3b557..c610f47373e4 100644
--- a/arch/x86/kernel/cpu/mtrr/if.c
+++ b/arch/x86/kernel/cpu/mtrr/if.c
@@ -106,17 +106,9 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
 
 	memset(line, 0, LINE_SIZE);
 
-	length = len;
-	length--;
-
-	if (length > LINE_SIZE - 1)
-		length = LINE_SIZE - 1;
-
+	length = strncpy_from_user(line, buf, LINE_SIZE - 1);
 	if (length < 0)
-		return -EINVAL;
-
-	if (copy_from_user(line, buf, length))
-		return -EFAULT;
+		return length;
 
 	linelen = strlen(line);
 	ptr = line + linelen - 1;