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Need to wait for epoch callbacks to complete before detaching a

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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
This commit is contained in:
Hans Petter Selasky 2019-06-28 10:49:04 +00:00
parent 131b2b7658
commit 0dbdf04125
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349507
1 changed files with 9 additions and 0 deletions
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9
sys/net/if.c
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@ -1127,6 +1127,15 @@ if_detach_internal(struct ifnet *ifp, int vmove, struct if_clone **ifcp)
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.