From 2a675089b129adf442de575617a7e3db5a42a794 Mon Sep 17 00:00:00 2001
From: MikeCAT <mikecat@users.noreply.github.com>
Date: Sat, 19 Dec 2015 22:52:11 +0900
Subject: [PATCH] fix memory region validation in argptr()

---
 syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/syscall.c b/syscall.c
index a84a921..9ae7536 100644
--- a/syscall.c
+++ b/syscall.c
@@ -58,7 +58,7 @@ argptr(int n, char **pp, int size)
 
   if(argint(n, &i) < 0)
     return -1;
-  if((uint)i >= proc->sz || (uint)i+size > proc->sz)
+  if(size < 0 || (uint)i >= proc->sz || (uint)i+size > proc->sz)
     return -1;
   *pp = (char*)i;
   return 0;