From 109fd094ea3ad0a7f92ed807cf3f0a3a08e06c25 Mon Sep 17 00:00:00 2001
From: Rafal Kupiec <belliash@codingworkshop.eu.org>
Date: Fri, 16 Feb 2024 19:05:53 +0100
Subject: [PATCH] Fix NULL pointer

---
 xtoskrnl/rtl/widestr.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/xtoskrnl/rtl/widestr.c b/xtoskrnl/rtl/widestr.c
index 9bc88eb..43ba75a 100644
--- a/xtoskrnl/rtl/widestr.c
+++ b/xtoskrnl/rtl/widestr.c
@@ -958,7 +958,7 @@ RtlpFormatWideStringArgumentSpecifier(IN PRTL_PRINT_CONTEXT Context,
             GuidArg = VA_ARG(*ArgumentList, PGUID);
         }
 
-        /* Make sure GUID is not NULL */
+        /* Make sure a pointer to GUID is not NULL */
         if(GuidArg != NULL)
         {
             /* Write formatted GUID string */
@@ -1143,8 +1143,12 @@ RtlpFormatWideStringArgumentSpecifier(IN PRTL_PRINT_CONTEXT Context,
             AnsiStrArg = VA_ARG(*ArgumentList, PANSI_STRING);
         }
 
-        /* Write formatted ANSI string value */
-        Status = RtlpWriteWideStringStringValue(Context, &FormatProperties, AnsiStrArg->Buffer, AnsiStrArg->Length);
+        /* Make sure a pointer to ANSI_STRING is not NULL */
+        if(AnsiStrArg != NULL)
+        {
+            /* Write formatted ANSI string value */
+            Status = RtlpWriteWideStringStringValue(Context, &FormatProperties, AnsiStrArg->Buffer, AnsiStrArg->Length);
+        }
     }
     else if(FormatProperties.VariableType == UnicodeString)
     {
@@ -1161,8 +1165,12 @@ RtlpFormatWideStringArgumentSpecifier(IN PRTL_PRINT_CONTEXT Context,
             UnicodeStrArg = VA_ARG(*ArgumentList, PUNICODE_STRING);
         }
 
-        /* Write formatted UNICODE string value */
-        Status = RtlpWriteWideStringValue(Context, &FormatProperties, UnicodeStrArg->Buffer, UnicodeStrArg->Length);
+        /* Make sure a pointer to UNICODE_STRING is not NULL */
+        if(UnicodeStrArg != NULL)
+        {
+            /* Write formatted UNICODE string value */
+            Status = RtlpWriteWideStringValue(Context, &FormatProperties, UnicodeStrArg->Buffer, UnicodeStrArg->Length);
+        }
     }
 
     /* Cleanup ArgumentsCopy object */