[PATCH 0/1] MR881: kernelbase: Fix reading stale information from IOSB.

[Jinoh Kang (＠iamahuman)]

Ensure IOSB Information (InternalHigh) is loaded after Status (Internal)
to avoid reading stale value from the Information (InternalHigh) field.

[PATCH 1/1] kernelbase: Fix reading stale information from IOSB.

[Jinoh Kang]

From: Jinoh Kang

Ensure IOSB Information (InternalHigh) is loaded after Status (Internal)
to avoid reading stale value from the Information (InternalHigh) field.
---
 dlls/kernelbase/file.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/dlls/kernelbase/file.c b/dlls/kernelbase/file.c
index 5ba7e0be419..62f65a1c068 100644
--- a/dlls/kernelbase/file.c
+++ b/dlls/kernelbase/file.c
@@ -3133,7 +3133,7 @@ BOOL WINAPI DECLSPEC_HOTPATCH GetOverlappedResultEx( HANDLE file, OVERLAPPED *ov

TRACE( "(%p %p %p %lu %d)\n", file, overlapped, result, timeout, alertable );

-    status = overlapped->Internal;
+    status = ReadAcquire((volatile LONG *)&overlapped->Internal);
     if (status == STATUS_PENDING)
     {
         if (!timeout)
@@ -3150,7 +3150,13 @@ BOOL WINAPI DECLSPEC_HOTPATCH GetOverlappedResultEx( HANDLE file, OVERLAPPED *ov
             return FALSE;
         }

-        status = overlapped->Internal;
+        /* Normally this does not require an atomic load, since the wait above
+         * acts as a barrier as long as the caller supplied the correct handle
+         * and nothing else interfered with signalling of I/O completion.
+         * However, we do it anyway for consistency and extra safety in case
+         * Windows takes the same precaution for misbehaving applications.
+         */
+        status = ReadAcquire((volatile LONG *)&overlapped->Internal);
         if (status == STATUS_PENDING) status = STATUS_SUCCESS;
     }