Prevent a NULL-pointer dereference when closing a ugen(4) node

in case the kernel failed to change the interface of a device.

Found the hardway by okan

diff --git a/sys/dev/usb/ugen.c b/sys/dev/usb/ugen.c
index 9f7eeac..e31c11d 100644 (file)
--- a/sys/dev/usb/ugen.c
+++ b/sys/dev/usb/ugen.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ugen.c,v 1.89 2015/09/15 13:37:44 dcoppa Exp $ */
+/*     $OpenBSD: ugen.c,v 1.90 2015/10/13 20:57:46 mpi Exp $ */
 /*     $NetBSD: ugen.c,v 1.63 2002/11/26 18:49:48 christos Exp $       */
 /*     $FreeBSD: src/sys/dev/usb/ugen.c,v 1.26 1999/11/17 22:33:41 n_hibma Exp $       */
 
@@ -925,10 +925,8 @@ ugen_set_interface(struct ugen_softc *sc, int ifaceidx, int altno)
                sce->iface = 0;
        }
 
-       /* change setting */
+       /* Try to change setting, if this fails put back the descriptors. */
        err = usbd_set_interface(iface, altno);
-       if (err)
-               return (err);
 
        id = usbd_get_interface_descriptor(iface);
        for (endptno = 0; endptno < id->bNumEndpoints; endptno++) {