On Tue, Feb 16, 2021 at 1:40 PM Yi-Hung Wei <yihung....@gmail.com> wrote:
>
> On Tue, Feb 16, 2021 at 1:06 PM Yifeng Sun <pkusunyif...@gmail.com> wrote:
> >
> > ovs-vswitchd could crash under these circumstances:
> > 1. When one bridge is being destroyed, ofproto_destroy() is called and
> > connmgr pointer of its ofproto struct is nullified. This ofproto struct is
> > deallocated through 'ovsrcu_postpone(ofproto_destroy_defer__, p);'.
> > 2. Before RCU enters quiesce state to actually free this ofproto struct,
> > revalidator thread calls udpif_revalidator(), which could handle
> > a learn flow and calls ofproto_flow_mod_learn(), it later calls
> > ofmonitor_report() and ofproto struct's connmgr pointer is accessed.
> >
LGTM, thanks. I guess this is hard to reproduce or create a test.
Do we need to worry about other places that use 'ofproto->connmgr'?
ex: there are a couple of places calling ofmonitor_flush(ofproto->connmgr);
> > The crash stack trace is shown below:
> >
> > 0 ofmonitor_report (mgr=0x0, rule=rule@entry=0x7fa4ac067c30,
> > event=event@entry=NXFME_ADDED,
> > reason=reason@entry=OFPRR_IDLE_TIMEOUT, abbrev_ofconn=0x0,
> > abbrev_xid=0, old_actions=old_actions@entry=0x0)
> > at ofproto/connmgr.c:2160
> > 1 0x00007fa4d6803495 in add_flow_finish (ofproto=0x55d9075d4ab0,
> > ofm=<optimized out>, req=req@entry=0x0)
> > at ofproto/ofproto.c:5221
> > 2 0x00007fa4d68036af in modify_flows_finish (req=0x0, ofm=0x7fa4980753f0,
> > ofproto=0x55d9075d4ab0)
> > at ofproto/ofproto.c:5823
> > 3 ofproto_flow_mod_finish (ofproto=0x55d9075d4ab0,
> > ofm=ofm@entry=0x7fa4980753f0, req=req@entry=0x0)
> > at ofproto/ofproto.c:8088
> > 4 0x00007fa4d680372d in ofproto_flow_mod_learn_finish
> > (ofm=ofm@entry=0x7fa4980753f0,
> > orig_ofproto=orig_ofproto@entry=0x0) at ofproto/ofproto.c:5439
> > 5 0x00007fa4d68072f9 in ofproto_flow_mod_learn (ofm=0x7fa4980753f0,
> > keep_ref=keep_ref@entry=true,
> > limit=<optimized out>, below_limitp=below_limitp@entry=0x0) at
> > ofproto/ofproto.c:5499
> > 6 0x00007fa4d6835d33 in xlate_push_stats_entry (entry=0x7fa498012448,
> > stats=stats@entry=0x7fa4d2701a10,
> > offloaded=offloaded@entry=false) at
> > ofproto/ofproto-dpif-xlate-cache.c:127
> > 7 0x00007fa4d6835e3a in xlate_push_stats (xcache=<optimized out>,
> > stats=stats@entry=0x7fa4d2701a10,
> > offloaded=offloaded@entry=false) at
> > ofproto/ofproto-dpif-xlate-cache.c:181
> > 8 0x00007fa4d6822046 in revalidate_ukey (udpif=udpif@entry=0x55d90760b240,
> > ukey=ukey@entry=0x7fa4b0191660,
> > stats=stats@entry=0x7fa4d2705118,
> > odp_actions=odp_actions@entry=0x7fa4d2701b50,
> > reval_seq=reval_seq@entry=5655486242,
> > recircs=recircs@entry=0x7fa4d2701b40, offloaded=false)
> > at ofproto/ofproto-dpif-upcall.c:2294
> > 9 0x00007fa4d6825aee in revalidate (revalidator=0x55d90769dd00) at
> > ofproto/ofproto-dpif-upcall.c:2683
> > 10 0x00007fa4d6825cf3 in udpif_revalidator (arg=0x55d90769dd00) at
> > ofproto/ofproto-dpif-upcall.c:936
> > 11 0x00007fa4d6259c9f in ovsthread_wrapper (aux_=<optimized out>) at
> > lib/ovs-thread.c:423
> > 12 0x00007fa4d582cea5 in start_thread () from /usr/lib64/libpthread.so.0
> > 13 0x00007fa4d504b96d in clone () from /usr/lib64/libc.so.6
> >
> > At the time of crash, the involved ofproto was already deallocated:
> >
> > (gdb) print *ofproto
> > $1 = ..., name = 0x55d907602820 "nsx-managed", ..., ports = {...,
> > one = 0x0, mask = 63, n = 0}, ..., connmgr = 0x0, ...
> >
> > This patch fixes it.
> >
> > VMware-BZ: #2700626
> > Signed-off-by: Yifeng Sun <pkusunyif...@gmail.com>
> > ---
>
> LGTM.
>
> Acked-by: Yi-Hung Wei <yihung....@gmail.com>
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