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 f04e72527604..3c1b12d461d1 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);