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Bug #6257

Updated by Victor Julien 11 months ago

On an inactive openvpn dev: 
 <pre> 
 # ip l show tun0 
 10: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN mode DEFAULT group default qlen 100 
     link/none 
 </pre> 

 Getting Suricata to shutdown fails: 
 <pre> 
 Info: runmodes: Using 2 live device(s). [RunModeSetLiveCaptureAutoFp:util-runmodes.c:143] 
 Info: pcap: tun0: running in 'auto' checksum mode. Detection of interface state will require 1000 packets [ReceivePcapThreadInit:source-pcap.c:522] 
 Info: ioctl: tun0: MTU 1500 [GetIfaceMTU:util-ioctl.c:110] 
 Info: pcap: tun0: snaplen set to 1524 [PcapOpenInterface:source-pcap.c:248] 
 Perf: ioctl: tun0: NIC offloading: RX unset TX unset [GetIfaceOffloadingLinux:util-ioctl.c:340] 
 Perf: ioctl: tun0: NIC offloading: SG: unset, GRO: unset, LRO: unset, TSO: unset, GSO: unset [GetIfaceOffloadingLinux:util-ioctl.c:385] 
 Info: pcap: tun1: running in 'auto' checksum mode. Detection of interface state will require 1000 packets [ReceivePcapThreadInit:source-pcap.c:522] 
 Info: ioctl: tun1: MTU 1500 [GetIfaceMTU:util-ioctl.c:110] 
 Info: pcap: tun1: snaplen set to 1524 [PcapOpenInterface:source-pcap.c:248] 
 Perf: ioctl: tun1: NIC offloading: RX unset TX unset [GetIfaceOffloadingLinux:util-ioctl.c:340] 
 Perf: ioctl: tun1: NIC offloading: SG: unset, GRO: unset, LRO: unset, TSO: unset, GSO: unset [GetIfaceOffloadingLinux:util-ioctl.c:385] 
 ... 
 Notice: suricata: Signature(s) loaded, Detect thread(s) activated. [PostRunStartedDetectSetup:suricata.c:2540] 
 Notice: suricata: Signal Received.    Stopping engine. [SuricataMainLoop:suricata.c:2828] 
 Error: threads: Engine unable to disable detect thread - "RX#01-tun0". Killing engine [TmThreadDisableReceiveThreads:tm-threads.c:1359] 
 </pre> 

 gdb shows: 
 <pre> 
 (gdb) bt 
 #0    0x00007ffff631199f in __GI___poll (fds=0x7fffe05dc210, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29 
 #1    0x00007ffff75c65ca in __interceptor_poll (fds=fds@entry=0x7fffe05dc210, nfds=nfds@entry=1, timeout=-1) at ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:3844 
 #2    0x00007ffff6455c4a in poll (__timeout=<optimized out>, __nfds=1, __fds=0x7fffe05dc210) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46 
 #3    pcap_wait_for_frames_mmap (handle=handle@entry=0x6180000fc080) at ./pcap-linux.c:4869 
 #4    0x00007ffff6455e75 in pcap_read_linux_mmap_v3 (handle=0x6180000fc080, max_packets=64, callback=0x555555b4cd36 <PcapCallbackLoop>, user=0x60e000e86fc0 "\200\300\017") at ./pcap-linux.c:5367 
 #5    0x0000555555b4d827 in ReceivePcapLoop (tv=0x6120000880c0, data=0x60e000e86fc0, slot=0x6060001067c0) at source-pcap.c:424 
 #6    0x0000555555832724 in TmThreadsSlotPktAcqLoop (td=0x6120000880c0) at tm-threads.c:316 
 #7    0x00007ffff70e7609 in start_thread (arg=<optimized out>) at pthread_create.c:477 
 #8    0x00007ffff631e133 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 
 </pre> 

 A big more debugging shows that @pcap_dispatch@ is called, but we never return from it. 

 If the pcap handle is set to nonblocking with @pcap_setnonblocking@ things do work, but the rest of the code isn't ready for this (100% cpu spin). 

 Same happens on a dummy device, so it should be easy to test. 

 It can be seen that @pcap_breakloop@ is called on the handle, but it is not resulting in breaking the loop.

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