From 895af77fe6ff7c73f198e852a40976ed102a49e4 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@mit.edu>
Date: Fri, 10 Apr 2015 07:15:06 -0400
Subject: check blockno passed to idestart

---
 ide.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'ide.c')

diff --git a/ide.c b/ide.c
index 96216ea..ed5a572 100644
--- a/ide.c
+++ b/ide.c
@@ -48,7 +48,7 @@ void
 ideinit(void)
 {
   int i;
-
+  
   initlock(&idelock, "ide");
   picenable(IRQ_IDE);
   ioapicenable(IRQ_IDE, ncpu - 1);
@@ -73,6 +73,8 @@ idestart(struct buf *b)
 {
   if(b == 0)
     panic("idestart");
+  if(b->blockno >= FSSIZE)
+    panic("incorrect blockno");
   int sector_per_block =  BSIZE/SECTOR_SIZE;
   int sector = b->blockno * sector_per_block;
 
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