dig crashes when interrupted while waiting for TCP response

Summary

dig crashes when interrupted while waiting for TCP response

BIND version used

• ~"v9.17": c52a3835
• ~"v9.11" and v9.16 not affected

Steps to reproduce

SIGINT dig while it's waiting for TCP response. 💥

1. Run python3 tcphang.py
2. Run dig -d 99 +tcp @127.0.0.1 .
3. SIGINT dig before it timeouts

(timeout --signal=SIGINT 1 dig -d 99 +tcp @127.0.0.1 . to do that in one go)

What is the current bug behavior?

dighost.c:1683: INSIST(query->readhandle == ((void *)0)) failed, back trace

(gdb) bt
#0  0x00007ffff6b15d22 in raise () from /usr/lib/libc.so.6
#1  0x00007ffff6aff862 in abort () from /usr/lib/libc.so.6
#2  0x00007ffff7a514b5 in isc_assertion_failed (file=0x55555557605c "dighost.c", line=1683, 
    type=isc_assertiontype_insist, cond=0x5555555770b8 "query->readhandle == ((void *)0)") at assertions.c:48
#3  0x0000555555567cf0 in _query_detach (queryp=0x7fffffffe5d8, file=0x55555557605c "dighost.c", line=4216)
    at dighost.c:1683
#4  0x0000555555571c3b in cancel_all () at dighost.c:4216
#5  0x0000555555562bc9 in dig_shutdown () at dig.c:2946
#6  0x0000555555562c2f in main (argc=4, argv=0x7fffffffe748) at dig.c:2957

What is the expected correct behavior?

Obviously, it should not crash.

Relevant configuration files

None, I believe.

Relevant logs and/or screenshots

``` $ timeout --signal=SIGINT 1 /tmp/main/bin/dig -d 99 +tcp @127.0.0.1 . setup_libs() setup_system() create_search_list() ndots is 1. timeout is 0. retries is 3. get_server_list() make_server(127.0.0.111) dig_query_setup parse_args() making new lookup make_empty_lookup() make_empty_lookup() = 0x7fd7117c0000->references = 1 digrc (open) main parsing -d main parsing 99 clone_lookup() make_empty_lookup() make_empty_lookup() = 0x7fd7117c1800->references = 1 clone_server_list() looking up 99 main parsing +tcp main parsing @127.0.0.1 make_server(127.0.0.1) main parsing . clone_lookup() make_empty_lookup() make_empty_lookup() = 0x7fd7117c3000->references = 1 clone_server_list() looking up . dig_startup() lock_lookup dighost.c:4186 success start_lookup() setup_lookup(0x7fd7117c1800) resetting lookup counter. using root origin recursive query AD query add_question() starting to render the message add_opt() done rendering create query 0x7fd710835000 linked to lookup 0x7fd7117c1800 dighost.c:2083:lookup_attach(0x7fd7117c1800) = 2 dighost.c:2587:new_query(0x7fd710835000) = 1 do_lookup() start_tcp(0x7fd710835000) dighost.c:2693:query_attach(0x7fd710835000) = 2 query->servname = 127.0.0.1

unlock_lookup dighost.c:4188 tcp_connected() tcp_connected(0x7fd710813300, success, 0x7fd710835000) lock_lookup dighost.c:3231 success dighost.c:3232:lookup_attach(0x7fd7117c1800) = 3 launch_next_query() dighost.c:3127:lookup_attach(0x7fd7117c1800) = 4 recvcount=1 have local timeout of 10000 dighost.c:3148:query_attach(0x7fd710835000) = 3 sending a request in launch_next_query dighost.c:3179:query_attach(0x7fd710835000) = 4 sendcount=1 dighost.c:3202:lookup_detach(0x7fd7117c1800) = 3 dighost.c:1676:query_detach(0x7fd710835000) = 3 dighost.c:3303:query_detach(0x7fd710835000) = 2 dighost.c:3304:lookup_detach(0x7fd7117c1800) = 2 unlock_lookup dighost.c:3305 send_done(0x7fd710813300, success, 0x7fd710835000) sendcount=0 lock_lookup dighost.c:2615 success dighost.c:2629:lookup_attach(0x7fd7117c1800) = 3 dighost.c:2648:query_detach(0x7fd710835000) = 1 dighost.c:2649:lookup_detach(0x7fd7117c1800) = 2 check_if_done() list full pending lookup 0x7fd7117c3000 unlock_lookup dighost.c:2652 destroy_lookup cancel_all() lock_lookup dighost.c:4202 success canceling pending query 0x7fd710835000, belonging to 0x7fd7117c1800 dighost.c:4216:query_detach(0x7fd710835000) = 0 dighost.c:1683: INSIST(query->readhandle == ((void *)0)) failed, back trace /tmp/main/lib/libisc-9.17.20.so(+0x4059d)[0x7fd7152cd59d] recv_done(0x7fd710813300, end of file, 0x7fd711579d90, 0x7fd710835000) lock_lookup dighost.c:3579 /tmp/main/lib/libisc-9.17.20.so(isc_assertion_failed+0x31)[0x7fd7152cd4b0] /tmp/main/bin/dig(+0x13cf0)[0x55d41bb0fcf0] /tmp/main/bin/dig(+0x1dc3b)[0x55d41bb19c3b] /tmp/main/bin/dig(+0xebc9)[0x55d41bb0abc9] /tmp/main/bin/dig(+0xec2f)[0x55d41bb0ac2f] /usr/lib/libc.so.6(__libc_start_main+0xd5)[0x7fd71437cb25] /tmp/main/bin/dig(+0x5e9e)[0x55d41bb01e9e] timeout: the monitored command dumped core

</details>

### Possible fixes

(If you can, link to the line of code that might be responsible for the
problem.)