1 files changed, 12 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c
index f04e725..3c1b12d 100644
--- a/arch/x86/kernel/cpu/mtrr/if.c
+++ b/arch/x86/kernel/cpu/mtrr/if.c
@@ -96,17 +96,24 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
 	unsigned long long base, size;
 	char *ptr;
 	char line[LINE_SIZE];
+	int length;
 	size_t linelen;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (!len)
-		return -EINVAL;
 
 	memset(line, 0, LINE_SIZE);
-	if (len > LINE_SIZE)
-		len = LINE_SIZE;
-	if (copy_from_user(line, buf, len - 1))
+
+	length = len;
+	length--;
+
+	if (length > LINE_SIZE - 1)
+		length = LINE_SIZE - 1;
+
+	if (length < 0)
+		return -EINVAL;
+
+	if (copy_from_user(line, buf, length))
 		return -EFAULT;
 
 	linelen = strlen(line);