From 514f368a8835657033937985dd04ec523a12a249 Mon Sep 17 00:00:00 2001
From: Aliaksandr <bsalex2025@gmail.com>
Date: Wed, 22 Apr 2026 23:22:54 +0300
Subject: [PATCH] Fix: Prevent usage of uninitialized memory

---
 dll/win32/kernel32/client/file/rw.c           |  4 +++
 .../rostests/apitests/kernel32/CMakeLists.txt |  1 +
 .../apitests/kernel32/ReadWriteFile.c         | 32 +++++++++++++++++++
 modules/rostests/apitests/kernel32/testlist.c |  4 +++
 4 files changed, 41 insertions(+)
 create mode 100644 modules/rostests/apitests/kernel32/ReadWriteFile.c

diff --git a/dll/win32/kernel32/client/file/rw.c b/dll/win32/kernel32/client/file/rw.c
index 8fc10d2ae37..a5bbc8fc3d5 100644
--- a/dll/win32/kernel32/client/file/rw.c
+++ b/dll/win32/kernel32/client/file/rw.c
@@ -78,6 +78,8 @@ WriteFile(IN HANDLE hFile,
     {
         IO_STATUS_BLOCK Iosb;
 
+        Iosb.Information = 0;
+
         Status = NtWriteFile(hFile,
                              NULL,
                              NULL,
@@ -189,6 +191,8 @@ ReadFile(IN HANDLE hFile,
     {
         IO_STATUS_BLOCK Iosb;
 
+        Iosb.Information = 0;
+
         Status = NtReadFile(hFile,
                             NULL,
                             NULL,
diff --git a/modules/rostests/apitests/kernel32/CMakeLists.txt b/modules/rostests/apitests/kernel32/CMakeLists.txt
index bba783049c3..862f07e1623 100644
--- a/modules/rostests/apitests/kernel32/CMakeLists.txt
+++ b/modules/rostests/apitests/kernel32/CMakeLists.txt
@@ -34,6 +34,7 @@ list(APPEND SOURCE
     MultiByteToWideChar.c
     Pipes.c
     PrivMoveFileIdentityW.c
+    ReadWriteFile.c
     QueueUserAPC.c
     SetComputerNameExW.c
     SetConsoleWindowInfo.c
diff --git a/modules/rostests/apitests/kernel32/ReadWriteFile.c b/modules/rostests/apitests/kernel32/ReadWriteFile.c
new file mode 100644
index 00000000000..9f4b75dc5b8
--- /dev/null
+++ b/modules/rostests/apitests/kernel32/ReadWriteFile.c
@@ -0,0 +1,32 @@
+/*
+ * PROJECT:     ReactOS api tests
+ * LICENSE:     LGPL-2.0-or-later (https://spdx.org/licenses/LGPL-2.0-or-later)
+ * PURPOSE:     Tests for ReadFile, WriteFile
+ * COPYRIGHT:   Copyright 2026 Aliaksandr Lebiadzevich (bsalex2025@gmail.com)
+ */
+
+ #include "precomp.h"
+
+START_TEST(ReadFile)
+{
+    BOOL Success;
+    DWORD BytesRead = 1;
+    char Buffer[1] = {0};
+
+    Success = ReadFile( INVALID_HANDLE_VALUE, Buffer, sizeof(Buffer), &BytesRead, NULL );
+
+    ok( !Success, "ReadFile should have returned FALSE" );
+    ok( BytesRead == 0, "BytesRead should be 0" );
+}
+
+START_TEST(WriteFile)
+{
+    BOOL Success;
+    DWORD BytesWritten = 1;
+    char Buffer[1] = {0};
+
+    Success = WriteFile( INVALID_HANDLE_VALUE, Buffer, sizeof(Buffer), &BytesWritten, NULL );
+
+    ok( !Success, "WriteFile should have returned FALSE" );
+    ok( BytesWritten == 0, "BytesWritten should be 0" );
+}
diff --git a/modules/rostests/apitests/kernel32/testlist.c b/modules/rostests/apitests/kernel32/testlist.c
index 3bec920a41c..2cb529726be 100644
--- a/modules/rostests/apitests/kernel32/testlist.c
+++ b/modules/rostests/apitests/kernel32/testlist.c
@@ -33,6 +33,7 @@ extern void func_Mailslot(void);
 extern void func_MultiByteToWideChar(void);
 extern void func_Pipes(void);
 extern void func_PrivMoveFileIdentityW(void);
+extern void func_ReadFile(void);
 extern void func_QueueUserAPC(void);
 extern void func_SetComputerNameExW(void);
 extern void func_SetConsoleWindowInfo(void);
@@ -43,6 +44,7 @@ extern void func_TerminateProcess(void);
 extern void func_TunnelCache(void);
 extern void func_UEFIFirmware(void);
 extern void func_WideCharToMultiByte(void);
+extern void func_WriteFile(void);
 
 const struct test winetest_testlist[] =
 {
@@ -77,6 +79,7 @@ const struct test winetest_testlist[] =
     { "MultiByteToWideChar",         func_MultiByteToWideChar },
     { "Pipes",                       func_Pipes },
     { "PrivMoveFileIdentityW",       func_PrivMoveFileIdentityW },
+    { "ReadFile",                    func_ReadFile },
     { "QueueUserAPC",                func_QueueUserAPC },
     { "SetComputerNameExW",          func_SetComputerNameExW },
     { "SetConsoleWindowInfo",        func_SetConsoleWindowInfo },
@@ -87,5 +90,6 @@ const struct test winetest_testlist[] =
     { "TunnelCache",                 func_TunnelCache },
     { "UEFIFirmware",                func_UEFIFirmware },
     { "WideCharToMultiByte",         func_WideCharToMultiByte },
+    { "WriteFile",                   func_WriteFile },
     { 0, 0 }
 };
-- 
2.45.1.windows.1