Zhiyi Zhang (@zhiyi) commented about dlls/winex11.drv/xvidmode.c:
static void xf86vm_free_modes(DEVMODEW *modes) { XF86VidModeModeInfo **xf86vm_modes;
BYTE *ptr = (BYTE *)modes - sizeof(xf86vm_modes);
if (modes) { assert(modes[0].dmDriverExtra == sizeof(XF86VidModeModeInfo *));
memcpy(&xf86vm_modes, (BYTE *)modes - sizeof(xf86vm_modes), sizeof(xf86vm_modes));
memcpy(&xf86vm_modes, ptr, sizeof(xf86vm_modes)); XFree(xf86vm_modes);
Let's move free(ptr) into the if (modes) branch or return early if modes is NULL.