[PATCH 2/2] imagehlp: Fix checksum calculation for odd sizes.

[Vijay Kiran Kamuju]

From: Michael Müller

Signed-off-by: Vijay Kiran Kamuju 
---
 dlls/imagehlp/modify.c          | 39 ++++++++++++++++-----------------
 dlls/imagehlp/tests/integrity.c |  2 +-
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/dlls/imagehlp/modify.c b/dlls/imagehlp/modify.c
index aa29ca7a02..2a0214bacc 100644
--- a/dlls/imagehlp/modify.c
+++ b/dlls/imagehlp/modify.c
@@ -60,26 +60,25 @@ BOOL WINAPI BindImageEx(
 /***********************************************************************
  *		CheckSum (internal)
  */
-static WORD CalcCheckSum(
-  DWORD StartValue, LPVOID BaseAddress, DWORD WordCount)
+static WORD CalcCheckSum(DWORD StartValue, LPVOID BaseAddress, DWORD ByteCount)
 {
-   LPWORD Ptr;
-   DWORD Sum;
-   DWORD i;
-
-   Sum = StartValue;
-   Ptr = (LPWORD)BaseAddress;
-   for (i = 0; i < WordCount; i++)
-     {
-	Sum += *Ptr;
-	if (HIWORD(Sum) != 0)
-	  {
-	     Sum = LOWORD(Sum) + HIWORD(Sum);
-	  }
-	Ptr++;
-     }
-
-   return (WORD)(LOWORD(Sum) + HIWORD(Sum));
+    LPWORD Ptr;
+    DWORD Sum, i;
+
+    Sum = StartValue;
+    Ptr = (LPWORD)BaseAddress;
+    for (i = ByteCount; i > 1; i -= 2)
+    {
+        Sum += *Ptr;
+        if (HIWORD(Sum) != 0)
+            Sum = LOWORD(Sum) + HIWORD(Sum);
+        Ptr++;
+    }
+
+    if (i == 1)
+        Sum += *(BYTE *)Ptr;
+
+    return (WORD)(LOWORD(Sum) + HIWORD(Sum));
 }

@@ -102,7 +101,7 @@ PIMAGE_NT_HEADERS WINAPI CheckSumMappedFile(
     BaseAddress, FileLength, HeaderSum, CheckSum
   );

-  CalcSum = (DWORD)CalcCheckSum(0, BaseAddress, (FileLength + 1) / sizeof(WORD));
+  CalcSum = (DWORD)CalcCheckSum(0, BaseAddress, FileLength);

__TRY
   {
diff --git a/dlls/imagehlp/tests/integrity.c b/dlls/imagehlp/tests/integrity.c
index b62b37cd4b..fff39127cf 100644
--- a/dlls/imagehlp/tests/integrity.c
+++ b/dlls/imagehlp/tests/integrity.c
@@ -350,7 +350,7 @@ static void test_pe_checksum(void)
     ret = pCheckSumMappedFile(buffer, 11, &checksum_orig, &checksum_new);
     ok(ret == NULL, "Expected NULL, got %p\n", ret);
     ok(checksum_orig == 0, "Expected 0, got %x\n", checksum_orig);
-    todo_wine ok(checksum_new == 0xaad7, "Expected 0xaad7, got %x\n", checksum_new);
+    ok(checksum_new == 0xaad7, "Expected 0xaad7, got %x\n", checksum_new);

/* test checksum of PE module */
     memset(buffer, 0x22, sizeof(buffer));