[squid-users] Massive crashes with 3.2.6 "assert "false" at line 689 Ip::Address invalid? with IsIPv4()=F, IsIPv6()=T"

All over a sudden, all our squid proxies started crashing. I produced
a backtrace:

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
[New Thread 0xb6052b40 (LWP 13083)]
[New Thread 0xb6011b40 (LWP 13084)]
[New Thread 0xb5fd0b40 (LWP 13085)]
[New Thread 0xb5f8fb40 (LWP 13086)]
[New Thread 0xb5f4eb40 (LWP 13087)]
[New Thread 0xb5f0db40 (LWP 13088)]
[New Thread 0xb5eccb40 (LWP 13089)]
[New Thread 0xb5e8bb40 (LWP 13090)]
[New Thread 0xb5e4ab40 (LWP 13091)]
[New Thread 0xb5e09b40 (LWP 13092)]
[New Thread 0xb5dc8b40 (LWP 13093)]
[New Thread 0xb5d87b40 (LWP 13094)]
[New Thread 0xb5d46b40 (LWP 13095)]
[New Thread 0xb5d05b40 (LWP 13096)]
[New Thread 0xb5cc4b40 (LWP 13097)]
[New Thread 0xb5c83b40 (LWP 13098)]
assert "false" at line 689
Ip::Address invalid? with IsIPv4()=F, IsIPv6()=T
ADDRESS: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
squid: Address.cc:689: void Ip::Address::GetAddrInfo(addrinfo*&, int)
const: Assertion false' failed.

Program received signal SIGABRT, Aborted.
0xb7fdd424 in __kernel_vsyscall ()
(gdb) bt
#0 0xb7fdd424 in __kernel_vsyscall ()
#1 0xb7be51df in raise () from /lib/i386-linux-gnu/libc.so.6
#2 0xb7be8825 in abort () from /lib/i386-linux-gnu/libc.so.6
#3 0xb7bde085 in ?? () from /lib/i386-linux-gnu/libc.so.6
#4 0xb7bde137 in __assert_fail () from /lib/i386-linux-gnu/libc.so.6
#5 0x082ca0ce in Ip::Address::GetAddrInfo (this=0xd8c3e3c, dst=@0xbffff324: 0xe85e9b0, force=0) at Address.cc:689
#6 0x082c3857 in comm_openex (sock_type=1, proto=6, addr=..., flags=1, tos=0 '\000', nfmark=0, note=0xe8b3c70 "[fe80::8cd8:b878:7d43:547e]") at comm.cc:525
#7 0x0831ced3 in Comm::ConnOpener::start (this=0xe48d9f0) at ConnOpener.cc:164
#8 0x082b8d94 in NullaryMemFunT<AsyncJob>::doDial (this=0xe8d6224) at ../../src/base/AsyncJobCalls.h:101
#9 0x082b8ee6 in JobDialer<AsyncJob>::dial (this=0xe8d6224, call=...) at ../../src/base/AsyncJobCalls.h:175
#10 0x082b9092 in AsyncCallT<NullaryMemFunT<AsyncJob> >::fire (this=0xe8d6208) at ../../src/base/AsyncCall.h:142
#11 0x082b5412 in AsyncCall::make (this=0xe8d6208) at AsyncCall.cc:36
#12 0x082b968d in AsyncCallQueue::fireNext (this=0x8900370) at AsyncCallQueue.cc:54
#13 0x082b9908 in AsyncCallQueue::fire (this=0x8900370) at AsyncCallQueue.cc:40
#14 0x0815500f in EventLoop::runOnce (this=0xbffff6a4) at EventLoop.cc:131
#15 0x081551c0 in EventLoop::run (this=0xbffff6a4) at EventLoop.cc:95
#16 0x081cd6c0 in SquidMain (argc=-1073744128, argv=0xbffff6a4) at main.cc:1501
#17 0x081ceebd in SquidMainSafe (argv=0xbffff7f4, argc=2) at main.cc:1216
#18 main (argc=2, argv=0xbffff7f4) at main.cc:1208
(gdb)

-- 
Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt@charite.de | http://www.charite.de