svn commit: r265232 - head/sys/net

[Alan Somers]

Author: asomers
Date: Fri May  2 16:24:09 2014
New Revision: 265232
URL: http://svnweb.freebsd.org/changeset/base/265232

Log:
  Fix a panic caused by doing "ifconfig -am" while a lagg is being destroyed.
  The thread that is destroying the lagg has already set sc->sc_psc=NULL when
  the "ifconfig -am" thread gets to lacp_req().  It tries to dereference
  sc->sc_psc and panics.  The solution is for lacp_req() to check the value of
  sc->sc_psc.  If NULL, harmlessly return an lacp_opreq structure full of
  zeros.  Full details in GNATS.
  
  PR:		kern/189003
  Reviewed by:	timeout on freebsd-net@
  MFC after:	3 weeks
  Sponsored by:	Spectra Logic Corporation

Modified:
  head/sys/net/ieee8023ad_lacp.c

Modified: head/sys/net/ieee8023ad_lacp.c
==============================================================================
--- head/sys/net/ieee8023ad_lacp.c	Fri May  2 16:15:34 2014	(r265231)
+++ head/sys/net/ieee8023ad_lacp.c	Fri May  2 16:24:09 2014	(r265232)
@@ -590,10 +590,20 @@ lacp_req(struct lagg_softc *sc, caddr_t 
 {
 	struct lacp_opreq *req = (struct lacp_opreq *)data;
 	struct lacp_softc *lsc = LACP_SOFTC(sc);
-	struct lacp_aggregator *la = lsc->lsc_active_aggregator;
+	struct lacp_aggregator *la;
 
-	LACP_LOCK(lsc);
 	bzero(req, sizeof(struct lacp_opreq));
+	
+	/* 
+	 * If the LACP softc is NULL, return with the opreq structure full of
+	 * zeros.  It is normal for the softc to be NULL while the lagg is
+	 * being destroyed.
+	 */
+	if (NULL == lsc)
+		return;
+
+	la = lsc->lsc_active_aggregator;
+	LACP_LOCK(lsc);
 	if (la != NULL) {
 		req->actor_prio = ntohs(la->la_actor.lip_systemid.lsi_prio);
 		memcpy(&req->actor_mac, &la->la_actor.lip_systemid.lsi_mac,