[PATCH] kernelbase: Avoid NULL-pointer dereferences.

[Gen Otsuji]

The codes after is_pointer(hmem) function, "if (hmem == NULL)" check
is needed to avoid null-pointer dereferences.
After struggling about 1 week, I found the C code "*p|=0", and if this
p is NULL,
NULL-pointer error will occur.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=49155
Signed-off-by: Gen Otsuji <otsugen0000 at gmail.com>
---
 dlls/kernelbase/memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dlls/kernelbase/memory.c b/dlls/kernelbase/memory.c
index 1efc3b6e82..5744193a74 100644
--- a/dlls/kernelbase/memory.c
+++ b/dlls/kernelbase/memory.c
@@ -641,6 +641,9 @@ HLOCAL WINAPI DECLSPEC_HOTPATCH LocalFree( HLOCAL hmem )
         ret = 0;
         if (is_pointer(hmem)) /* POINTER */
         {
+            if (hmem == NULL)
+                ret = NULL;
+            else
             if (!HeapFree( GetProcessHeap(), HEAP_NO_SERIALIZE, hmem ))
             {
                 SetLastError( ERROR_INVALID_HANDLE );
@@ -690,6 +693,7 @@ LPVOID WINAPI DECLSPEC_HOTPATCH LocalLock( HLOCAL hmem )

     if (is_pointer( hmem ))
     {
+       if (hmem == NULL) return NULL;
         __TRY
         {
             volatile char *p = hmem;
-- 
2.26.2