From: Nathaniel Wesley Filardo <nwf@cs.jhu.edu>
Date: Sat, 7 Nov 2015 05:38:40 +0000 (-0500)
Subject: Add sanity check panic for CRTC interactions
X-Git-Url: https://hydra-www.ietfng.org/gitweb/?a=commitdiff_plain;h=86c10e34e8f2ae18b8c52ac63cbcb7e120e58f5b;p=xv6-public

Add sanity check panic for CRTC interactions
---

diff --git a/console.c b/console.c
index a017e3a..f11abf3 100644
--- a/console.c
+++ b/console.c
@@ -149,6 +149,9 @@ cgaputc(int c)
     if(pos > 0) --pos;
   } else
     crt[pos++] = (c&0xff) | 0x0700;  // black on white
+
+  if(pos > 25*80)
+    panic("pos overflow");
   
   if((pos/80) >= 24){  // Scroll up.
     memmove(crt, crt+80, sizeof(crt[0])*23*80);