From: Hermès Bélusca-Maïto <hermes.belusca-maito@reactos.org>
Date: Sun, 28 Sep 2014 22:35:05 +0000 (+0000)
Subject: [NTVDM]: Use the 0xCC (int 3) instruction as the memory fill byte.
X-Git-Tag: backups/0.3.17@66124~360
X-Git-Url: https://git.reactos.org/?p=reactos.git;a=commitdiff_plain;h=90d370dbb659af5bc9d7e99a4da0643e56ab4009

[NTVDM]: Use the 0xCC (int 3) instruction as the memory fill byte.

svn path=/trunk/; revision=64383
---

diff --git a/reactos/subsystems/ntvdm/emulator.c b/reactos/subsystems/ntvdm/emulator.c
index 18121b0159e..06d1e234676 100644
--- a/reactos/subsystems/ntvdm/emulator.c
+++ b/reactos/subsystems/ntvdm/emulator.c
@@ -549,8 +549,12 @@ BOOLEAN EmulatorInitialize(HANDLE ConsoleInput, HANDLE ConsoleOutput)
         wprintf(L"FATAL: Failed to allocate VDM memory.\n");
         return FALSE;
     }
-    // For diagnostics purposes!!
-    RtlFillMemory(BaseAddress, MAX_ADDRESS, 0xFF);
+    /*
+     * For diagnostics purposes, we fill the memory with INT 0x03 codes
+     * so that if a program wants to execute random code in memory, we can
+     * retrieve the exact CS:IP where the problem happens.
+     */
+    RtlFillMemory(BaseAddress, MAX_ADDRESS, 0xCC);
 
     /* Initialize I/O ports */
     /* Initialize RAM */