[tkreuzer] 76020: [RTL/x64] Fix logic in RtlpTryToUnwindEpilog

Author: tkreuzer
Date: Sun Oct  1 14:36:21 2017
New Revision: 76020

URL: http://svn.reactos.org/svn/reactos?rev=76020&view=rev
Log:
[RTL/x64] Fix logic in RtlpTryToUnwindEpilog

Modified:
    trunk/reactos/sdk/lib/rtl/amd64/unwind.c

Modified: trunk/reactos/sdk/lib/rtl/amd64/unwind.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/sdk/lib/rtl/amd64/unwind.c…
==============================================================================
--- trunk/reactos/sdk/lib/rtl/amd64/unwind.c	[iso-8859-1] (original)
+++ trunk/reactos/sdk/lib/rtl/amd64/unwind.c	[iso-8859-1] Sun Oct  1 14:36:21 2017
@@ -295,9 +295,9 @@
         }
     }
 
-    /* Loop the following instructions */
-    EndAddress = FunctionEntry->EndAddress + ImageBase;
-    while((DWORD64)InstrPtr < EndAddress)
+    /* Loop the following instructions before the ret */
+    EndAddress = FunctionEntry->EndAddress + ImageBase - 1;
+    while ((DWORD64)InstrPtr < EndAddress)
     {
         Instr = *(DWORD*)InstrPtr;
 
@@ -315,20 +315,28 @@
         if ( (Instr & 0xf8fb) == 0x5841 )
         {
             /* Opcode is pop r8 .. r15 */
-            Reg = (Instr & 0x7) + 8;
+            Reg = ((Instr >> 8) & 0x7) + 8;
             PopReg(&LocalContext, Reg);
             InstrPtr += 2;
             continue;
         }
 
-        /* Check for retn / retf */
-        if ( (Instr & 0xf7) == 0xc3 )
-        {
-            /* We are finished */
-            break;
-        }
-
         /* Opcode not allowed for Epilog */
+        return FALSE;
+    }
+
+    /* Check if we are at the ret instruction */
+    if ((DWORD64)InstrPtr != EndAddress)
+    {
+        /* If we went past the end of the function, something is broken! */
+        ASSERT((DWORD64)InstrPtr <= EndAddress);
+        return FALSE;
+    }
+
+    /* Make sure this is really a ret instruction */
+    if (*InstrPtr != 0xc3)
+    {
+        ASSERT(FALSE);
         return FALSE;
     }
 
@@ -414,7 +422,7 @@
         }
     }
 
-    /* Process the left Ops */
+    /* Process the remaining unwind ops */
     while (i < UnwindInfo->CountOfCodes)
     {
         UnwindCode = UnwindInfo->UnwindCode[i];