Author: hselasky
Date: Fri Jun 28 10:49:04 2019
New Revision: 349507
URL: https://svnweb.freebsd.org/changeset/base/349507
Log:
Need to wait for epoch callbacks to complete before detaching a
network interface.
This particularly manifests itself when an INP has multicast options
attached during a network interface detach. Then the IPv4 and IPv6
leave group call which results from freeing the multicast address, may
access a freed ifnet structure. These are the steps to reproduce:
service mdnsd onestart # installed from ports
ifconfig epair create
ifconfig epair0a 0/24 up
ifconfig epair0a destroy
Tested by: pho @
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/net/if.c
Modified: head/sys/net/if.c
==============================================================================
--- head/sys/net/if.c Fri Jun 28 10:38:56 2019 (r349506)
+++ head/sys/net/if.c Fri Jun 28 10:49:04 2019 (r349507)
@@ -1127,6 +1127,15 @@ if_detach_internal(struct ifnet *ifp, int vmove, struc
curvnet->vnet_ifcnt--;
#endif
epoch_wait_preempt(net_epoch_preempt);
+
+ /*
+ * Ensure all pending EPOCH(9) callbacks have been executed. This
+ * fixes issues about late destruction of multicast options
+ * which lead to leave group calls, which in turn access the
+ * belonging ifnet structure:
+ */
+ epoch_drain_callbacks(net_epoch_preempt);
+
/*
* In any case (destroy or vmove) detach us from the groups
* and remove/wait for pending events on the taskq.
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