On Fri, Mar 22, 2024 at 11:04 PM Ilya Maximets <[email protected]> wrote: > > On 3/22/24 17:36, Mike Pattrick wrote: > > On Fri, Mar 22, 2024 at 10:41 AM Ilya Maximets <[email protected]> wrote: > >> > >> Recirculation involves re-parsing the packet from scratch and that > >> process is not aware of multiple header levels nor the inner/outer > >> offsets. So, it overwrites offsets with new ones from the outermost > >> headers and sets offloading flags that change their meaning when > >> the packet is marked for tunnel offloading. > >> > >> For example: > >> > >> 1. TCP packet enters OVS. > >> 2. TCP packet gets encapsulated into UDP tunnel. > >> 3. Recirculation happens. > >> 4. Packet is re-parsed after recirculation with miniflow_extract() > >> or similar function. > >> 5. Packet is marked for UDP checksumming because we parse the > >> outermost set of headers. But since it is tunneled, it means > >> inner UDP checksumming. And that makes no sense, because the > >> inner packet is TCP. > >> > >> This is causing packet drops due to malformed packets or even > >> assertions and crashes in the code that is trying to fixup checksums > >> for packets using incorrect metadata: > >> > >> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior > >> > >> lib/packets.c:2061:15: runtime error: > >> member access within null pointer of type 'struct udp_header' > >> > >> 0 0xbe5221 in packet_udp_complete_csum lib/packets.c:2061:15 > >> 1 0x7e5662 in dp_packet_ol_send_prepare lib/dp-packet.c:638:9 > >> 2 0x96ef89 in netdev_send lib/netdev.c:940:9 > >> 3 0x818e94 in dp_netdev_pmd_flush_output_on_port lib/dpif-netdev.c:5577:9 > >> 4 0x817606 in dp_netdev_pmd_flush_output_packets > >> lib/dpif-netdev.c:5618:27 > >> 5 0x81cfa5 in dp_netdev_process_rxq_port lib/dpif-netdev.c:5677:9 > >> 6 0x7eefe4 in dpif_netdev_run lib/dpif-netdev.c:7001:25 > >> 7 0x610e87 in type_run ofproto/ofproto-dpif.c:367:9 > >> 8 0x5b9e80 in ofproto_type_run ofproto/ofproto.c:1879:31 > >> 9 0x55bbb4 in bridge_run__ vswitchd/bridge.c:3281:9 > >> 10 0x558b6b in bridge_run vswitchd/bridge.c:3346:5 > >> 11 0x591dc5 in main vswitchd/ovs-vswitchd.c:130:9 > >> 12 0x172b89 in __libc_start_call_main (/lib64/libc.so.6+0x27b89) > >> 13 0x172c4a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x27c4a) > >> 14 0x47eff4 in _start (vswitchd/ovs-vswitchd+0x47eff4) > >> > >> Tests added for both IPv4 and IPv6 cases. Though IPv6 test doesn't > >> trigger the issue it's better to have a symmetric test. > >> > >> Fixes: 084c8087292c ("userspace: Support VXLAN and GENEVE TSO.") > >> Reported-at: > >> https://mail.openvswitch.org/pipermail/ovs-discuss/2024-March/053014.html > >> Signed-off-by: Ilya Maximets <[email protected]> > >> --- > > > > I have tested this, and it does fix the segfault here. > > > > Acked-by: Mike Pattrick <[email protected]> > > > > Thanks! Applied and backported to 3.3. > > We can think of alternative solutions on top of this fix, but I don't > see any easy ones that would cover all the cases for now.
Would it be possible to call dp_netdev_input__() with a new flag (or perhaps rely on md_is_valid)? If this flag is set, dp_netdev_input__ would save *lX_ofs + ol_flags before calling miniflow_extract, then restore those info afterwards (and maybe check that outer offsets are still the same as a sanity check?). -- David Marchand _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
