[PATCH v3 2/2] kernelbase: Fix stack overflow by DefineDosDeviceW().

[Xu Wei]

Signed-off-by: Xu Wei 
---
 dlls/kernelbase/volume.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/dlls/kernelbase/volume.c b/dlls/kernelbase/volume.c
index d513dda1f9d..be68721020e 100644
--- a/dlls/kernelbase/volume.c
+++ b/dlls/kernelbase/volume.c
@@ -384,7 +384,7 @@ err_ret:
  */
 BOOL WINAPI DECLSPEC_HOTPATCH DefineDosDeviceW( DWORD flags, const WCHAR *device, const WCHAR *target )
 {
-    WCHAR link_name[15] = L"\DosDevices\";
+    WCHAR *link_name = NULL;
     UNICODE_STRING nt_name, nt_target;
     OBJECT_ATTRIBUTES attr;
     NTSTATUS status;
@@ -395,17 +395,28 @@ BOOL WINAPI DECLSPEC_HOTPATCH DefineDosDeviceW( DWORD flags, const WCHAR *device
     if (flags & ~(DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION))
         FIXME("Ignoring flags %#x.\n", flags & ~(DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION));

-    lstrcatW( link_name, device );
+    if (!(link_name = HeapAlloc( GetProcessHeap(), 0, sizeof(L"\DosDevices\") + (device ? lstrlenW(device) * sizeof(WCHAR) : 0))))
+    {
+        SetLastError(ERROR_OUTOFMEMORY);
+        return FALSE;
+    }
+
+    lstrcpyW( link_name, L"\DosDevices\" );
+    if (device) lstrcatW( link_name, device );
     RtlInitUnicodeString( &nt_name, link_name );
     InitializeObjectAttributes( &attr, &nt_name, OBJ_CASE_INSENSITIVE | OBJ_PERMANENT, 0, NULL );
     if (flags & DDD_REMOVE_DEFINITION)
     {
         if (!set_ntstatus( NtOpenSymbolicLinkObject( &handle, 0, &attr ) ))
+        {
+            HeapFree( GetProcessHeap(), 0, link_name );
             return FALSE;
+        }

status = NtMakeTemporaryObject( handle );
         NtClose( handle );

+        HeapFree( GetProcessHeap(), 0, link_name );
         return set_ntstatus( status );
     }

@@ -414,6 +425,7 @@ BOOL WINAPI DECLSPEC_HOTPATCH DefineDosDeviceW( DWORD flags, const WCHAR *device
         if (!RtlDosPathNameToNtPathName_U( target, &nt_target, NULL, NULL))
         {
             SetLastError( ERROR_PATH_NOT_FOUND );
+            HeapFree( GetProcessHeap(), 0, link_name );
             return FALSE;
         }
     }
@@ -422,6 +434,7 @@ BOOL WINAPI DECLSPEC_HOTPATCH DefineDosDeviceW( DWORD flags, const WCHAR *device

if (!(status = NtCreateSymbolicLinkObject( &handle, SYMBOLIC_LINK_ALL_ACCESS, &attr, &nt_target )))
         NtClose( handle );
+    HeapFree( GetProcessHeap(), 0, link_name );
     return set_ntstatus( status );
 }