Reset freed HGDI_DC

CVE-2020-4031 thanks to @antonio-morales for finding this.

(cherry picked from commit f753c25ad3d5dae7890fe73cfb3c091c015d97ed)

diff --git a/libfreerdp/gdi/graphics.c b/libfreerdp/gdi/graphics.c
index f63df39..60d82ae 100644 (file)
--- a/libfreerdp/gdi/graphics.c
+++ b/libfreerdp/gdi/graphics.c
@@ -93,6 +93,7 @@ static BOOL gdi_Bitmap_New(rdpContext* context, rdpBitmap* bitmap)
        if (!gdi_bitmap->bitmap)
        {
                gdi_DeleteDC(gdi_bitmap->hdc);
+               gdi_bitmap->hdc = NULL;
                return FALSE;
        }