[ovs-discuss] openvswitch-2.14.0 crashes

[Miroslav Kubiczek]

We are not using DPDK in that environment. How can I check whether we use userspace datapath?

Thanks
M.
________________________________
From: Ben Pfaff <blp at ovn.org>
Sent: Wednesday, June 2, 2021 8:39 PM
To: Miroslav Kubiczek <Miroslav.Kubiczek at adaptivemobile.com>
Cc: bugs at openvswitch.org <bugs at openvswitch.org>
Subject: Re: [ovs-discuss] openvswitch-2.14.0 crashes

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On Mon, May 31, 2021 at 04:44:11PM +0000, Miroslav Kubiczek wrote:
> Hello,
> We observe a crash with certain packets (BGP UPDATE with 2096 bytes whereas MTU was 1500):
>
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> Core was generated by `ovs-vswitchd unix:/var/run/openvswitch/db.sock -vconsole:emer -vsyslog:err -vfi'.
> Program terminated with signal 11, Segmentation fault.
> #0  dp_packet_set_size (v=572, b=0x0) at lib/dp-packet.h:578
> 578         b->mbuf.data_len = (uint16_t)v;  /* Current seg length. */
> Missing separate debuginfos, use: debuginfo-install glibc-2.17-307.el7.1.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.15.1-46.el7.x86_64 libatomic-4.8.5-44.el7.x86_64 libcom_err-1.42.9-17.el7.x86_64 libevent-2.0.21-4.el7.x86_64 libgcc-4.8.5-39.el7.x86_64 libpcap-1.5.3-12.el7.x86_64 libselinux-2.5-15.el7.x86_64 libunwind-1.2-2.el7.x86_64 numactl-libs-2.0.12-5.el7.x86_64 openssl-libs-1.0.2k-19.el7.x86_64 pcre-8.32-17.el7.x86_64 python-libs-2.7.5-88.el7.x86_64 unbound-libs-1.6.6-3.el7.x86_64 zlib-1.2.7-18.el7.x86_64
> (gdb) backtrace
> #0  dp_packet_set_size (v=572, b=0x0) at lib/dp-packet.h:578
> #1  netdev_linux_batch_rxq_recv_sock (rx=rx at entry=0x20b1c90, mtu=<optimized out>, batch=batch at entry=0x7ffcf27baee0) at lib/netdev-linux.c:1306

This looks something of a weird case overall, because it suggests that
you're using the userspace datapath but not DPDK network devices.  Is
that correct?

This crash appears to be here:

        if (mmsgs[i].msg_len > std_len) {
            /* Build a single linear TSO packet by prepending the data from
             * std_len buffer to the aux_buf. */
            pkt = rx->aux_bufs[i];
            dp_packet_set_size(pkt, mmsgs[i].msg_len - std_len);

Ending up passing a null 'pkt' to dp_packet_set_size() indicates that
somehow aux_bufs[i] didn't get initialized.  I don't see how that would
happen.

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