svn commit: r313108 - stable/11/sys/net

[Alan Somers]

Author: asomers
Date: Thu Feb  2 21:05:55 2017
New Revision: 313108
URL: https://svnweb.freebsd.org/changeset/base/313108

Log:
  MFC r310180, r310327
  
  r310180:
  Fix panic during lagg destruction with simultaneous status check
  
  If you run "ifconfig lagg0 destroy" and "ifconfig lagg0" at the same time a
  page fault may result. The first process will destroy ifp->if_lagg in
  lagg_clone_destroy (called by if_clone_destroy). Then the second process
  will observe that ifp->if_lagg is NULL at the top of lagg_port_ioctl and
  goto fallback: where it will promptly dereference ifp->if_lagg anyway.
  
  The solution is to repeat the NULL check for ifp->if_lagg
  
  MFC after:	4 weeks
  Sponsored by:	Spectra Logic Corp
  Differential Revision:	https://reviews.freebsd.org/D8512
  
  r310327:
  Remove stray debugging code from r310180
  
  Reported by:	rstone
  Pointy hat to:	asomers
  MFC after:	3 weeks
  X-MFC-with:	310180
  Sponsored by:	Spectra Logic Corp

Modified:
  stable/11/sys/net/if_lagg.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/net/if_lagg.c
==============================================================================
--- stable/11/sys/net/if_lagg.c	Thu Feb  2 20:30:50 2017	(r313107)
+++ stable/11/sys/net/if_lagg.c	Thu Feb  2 21:05:55 2017	(r313108)
@@ -1022,7 +1022,7 @@ lagg_port_ioctl(struct ifnet *ifp, u_lon
 	return (error);
 
 fallback:
-	if (lp->lp_ioctl != NULL)
+	if (lp != NULL && lp->lp_ioctl != NULL)
 		return ((*lp->lp_ioctl)(ifp, cmd, data));
 
 	return (EINVAL);