[PATCH v8 8/8] check correct number of bytes

[Etaash Mathamsetty]

From: Etaash Mathamsetty

might be an issue?
---
 dlls/ntoskrnl.exe/instr.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/dlls/ntoskrnl.exe/instr.c b/dlls/ntoskrnl.exe/instr.c
index 2205def6be5..0122672e9fb 100644
--- a/dlls/ntoskrnl.exe/instr.c
+++ b/dlls/ntoskrnl.exe/instr.c
@@ -893,34 +893,42 @@ static DWORD emulate_instruction( EXCEPTION_RECORD *rec, CONTEXT *context )
     case 0x38:
     case 0x39: /* cmp r/m r/m */
     {
-        BYTE* data = INSTR_GetOperandAddr(context, instr + 1, prefixlen + 1, long_addr, rex, segprefix, &len);
-        BYTE* data2 = INSTR_GetOperandAddr(context, instr + 2, prefixlen + 2, long_addr, rex, segprefix, &len);
-        SIZE_T offset = data - user_shared_data;
-        SIZE_T offset2 = data2 - user_shared_data;
+        ULONG64* data = (ULONG64*)INSTR_GetOperandAddr(context, instr + 1, prefixlen + 1, long_addr, rex, segprefix, &len);
+        ULONG64* data2 = (ULONG64*)INSTR_GetOperandAddr(context, instr + 2, prefixlen + 2, long_addr, rex, segprefix, &len);
+        SIZE_T offset = (BYTE*)data - user_shared_data;
+        SIZE_T offset2 = (BYTE*)data2 - user_shared_data;
         SIZE_T data_size = get_op_size(long_op, rex);
         BOOL is_user_shared_data = FALSE;
+        ULONG64 cmp1, cmp2, bitmask;
         if(offset <= KSHARED_USER_DATA_PAGE_SIZE - data_size)
         {
             TRACE("USD offset %#x at %p\n",(unsigned int) offset, (void*) context->Rip);
-            data = (BYTE*)(wine_user_shared_data + offset);
+            data = (ULONG64*)(wine_user_shared_data + offset);
             is_user_shared_data = TRUE;
         }
         if(offset2 <= KSHARED_USER_DATA_PAGE_SIZE - data_size)
         {
             TRACE("USD offset %#x at %p\n", (unsigned int) offset2, (void*) context->Rip);
-            data2 = (BYTE*)(wine_user_shared_data + offset2);
+            data2 = (ULONG64*)(wine_user_shared_data + offset2);
             is_user_shared_data = TRUE;
         }
-        if(is_user_shared_data){
+        if(is_user_shared_data)
+        {
             /* clear ZF and CF */
             context->EFlags &= ~(1UL << 6);
             context->EFlags &= ~(1UL);

-            if(*data == *data2)
+            bitmask = ((1ULL << (8 * data_size)) - 1); 
+            /* FIXME("bitmask %llx\n", bitmask); */
+
+            cmp1 = (*data) & bitmask; 
+            cmp2 = (*data2) & bitmask;
+
+            if(cmp1 == cmp2)
             {
                 context->EFlags |= (1UL << 6); /* ZF */
             }
-            else if(*data < *data2){
+            else if(cmp1 < cmp2){
                 context->EFlags |= 1UL; /* CF */
             }
             context->Rip += prefixlen + len + 1;