From a3716901ce8b47e2637db087724fbe1f56122819 Mon Sep 17 00:00:00 2001
From: Adrien Bourmault <neox@os-k.eu>
Date: Wed, 22 May 2019 08:11:50 +0200
Subject: [PATCH] Stack Overflow detected !

---
 include/mm/mm.h           | 10 ++++++++++
 kaleid/kernel/ke/idt.c    | 32 ++++++++++++++++++++------------
 kaleid/kernel/mm/paging.c | 22 +++++++++++++++-------
 3 files changed, 45 insertions(+), 19 deletions(-)

diff --git a/include/mm/mm.h b/include/mm/mm.h
index 897e7a5..f0c7707 100644
--- a/include/mm/mm.h
+++ b/include/mm/mm.h
@@ -158,6 +158,16 @@ extern void MmLoadGdt(GdtPtr_t *gdtPtr, ushort tssOffset);
 //
 extern void MmStoreGdt(void);
 
+//
+// Returns the address of the stack guard pages
+//
+void *MmGetStackGuards(char rank);
+
+//
+// Translate a virtual address into physical address
+//
+void *MmTranslateKPageToAddr(void *rank);
+
 //----------------------------------------------------------------------------//
 
 #endif
diff --git a/kaleid/kernel/ke/idt.c b/kaleid/kernel/ke/idt.c
index 873c2ad..f877b92 100644
--- a/kaleid/kernel/ke/idt.c
+++ b/kaleid/kernel/ke/idt.c
@@ -26,13 +26,12 @@
 #include <init/boot.h>
 #include <ke/idt.h>
 #include <io/vga.h>
+#include <mm/mm.h>
 
 IdtEntry_t idt[256] = { 0 };
 IdtPtr_t _KeIdtPtr;
 bool KeIdtIsInitialized = 0;
 
-extern ulong *MmStackGuards[2];
-
 static ISRList_t isrList = { 0 };
 
 static char *ExceptionsChar[32] = {
@@ -74,9 +73,6 @@ static void EnablePIC(void);
 static void EarlyExceptionHandler(ISRFrame_t *regs);
 static void DoubleFaultHandler(ISRFrame_t *regs);
 
-//paging.c
-ulong *MmGetStackGuards(void);
-
 //
 // Registers an isr with his IRQ to handle driver interrupts
 //
@@ -305,18 +301,30 @@ static void EarlyExceptionHandler(ISRFrame_t *regs)
 
 static void DoubleFaultHandler(ISRFrame_t *regs)
 {
-    bprintf(BStdOut, "test : %p\n", (ulong)(MmGetStackGuards())[0] + 4*KB);
+    ulong StackGuardOne = (ulong)MmGetStackGuards(0);
+    ulong StackGuardTwo = (ulong)MmGetStackGuards(1);
 
-    if (regs->rsp <= (ulong)(MmGetStackGuards())[0] + 4*KB) {
+    if (regs->rsp <= StackGuardTwo + 4*KB) {
         bprintf(BStdOut,
-            "\n\n%CPANIC\n[ISR 0x8] Irrecoverable Kernel Stack Overflow%s\n\n"
-                     "  Error code : 0x%x (%b)",
+            "\n\n%CPANIC\n[ISR 0x8] Irrecoverable Kernel Stack Overflow\n\n"
+                     "  Double Fault Error code : %#x (%b)\n"
+                     "  Stack Guard bypassed    : %#x",
 
                      VGA_COLOR_LIGHT_RED,
-                     regs->intNo,
-                     ExceptionsChar[regs->intNo],
                      regs->ErrorCode,
-                     regs->ErrorCode
+                     regs->ErrorCode,
+                     StackGuardTwo
+                 );
+    } else if (regs->rsp <= StackGuardOne) {
+        bprintf(BStdOut,
+            "\n\n%CPANIC\n[ISR 0x8] Irrecoverable Kernel Stack Underflow\n\n"
+                     "  Double Fault Error code : %#x (%b)\n"
+                     "  Stack Guard bypassed    : %#x",
+
+                     VGA_COLOR_LIGHT_RED,
+                     regs->ErrorCode,
+                     regs->ErrorCode,
+                     StackGuardOne
                  );
     } else {
         bprintf(BStdOut,
diff --git a/kaleid/kernel/mm/paging.c b/kaleid/kernel/mm/paging.c
index d6ec008..6f81444 100644
--- a/kaleid/kernel/mm/paging.c
+++ b/kaleid/kernel/mm/paging.c
@@ -20,6 +20,7 @@ typedef ulong    pte_t;
 void MmLoadPML4(void *);
 void MmEnableWriteProtect(void);
 void MmDisableWriteProtect(void);
+void *MmGetStackGuards(char rank);
 
 enum
 {
@@ -67,7 +68,7 @@ void MmInitPaging(void)
         // STACK GUARD PAGE
         if ((ulong)(i*KPAGESIZE) == (ulong)BtLoaderInfo.stackEndAddr) {
             MmPT[i] = ((ulong)(i*KPAGESIZE));
-            MmStackGuards[0] = i;
+            MmStackGuards[0] = ((ulong)(i*KPAGESIZE));
             continue;
         }
 
@@ -79,7 +80,7 @@ void MmInitPaging(void)
         // STACK GARD PAGE
         if ((ulong)(i*KPAGESIZE) == (ulong)BtLoaderInfo.kernelEndAddr) {
             MmPT[i] = ((ulong)(i*KPAGESIZE));
-            MmStackGuards[1] = i;
+            MmStackGuards[1] = ((ulong)(i*KPAGESIZE));
             continue;
         }
 
@@ -160,6 +161,18 @@ void MmReloadPaging(void)
     DebugLog("Stack Guards at %p, %p\n", MmStackGuards[0], MmStackGuards[1]);
 }
 
+// Returns the rank of the Stack Guards
+void *MmGetStackGuards(char rank)
+{
+    return (void *)MmStackGuards[(int)rank];
+}
+
+// Returns an address corresponding to the PT rank
+void *MmTranslateKPageToAddr(void *rank)
+{
+    return (void *)MmPT[(ulong)rank];
+}
+
 //
 // Page fault handler
 //
@@ -186,8 +199,3 @@ void MmActivatePageHandler(void)
 {
     KeRegisterISR(PagingHandler, 0xe);
 }
-
-ulong *MmGetStackGuards(void)
-{
-    return &MmStackGuards[0];
-}