tree 49cbc68a8afff8d389a799c3296e100a770ba57e
parent 74d7b6e99239727eb23f8fb79731110ad4830524
author William Dauchy <wdauchy@gmail.com> 1614210793 +0100
committer Christopher Faulet <cfaulet@haproxy.com> 1614233648 +0100

BUG/MEDIUM: contrib/prometheus-exporter: fix segfault in listener name dump

We need to check whether listener is empty before doing anything; in
that case, we were trying to dump listerner name while name is null. So
simply move the counters check above, which validate all possible cases
when the listener is empty. This is very similar to what is done in
stats.c

see also the trace:

  Thread 1 "haproxy" received signal SIGSEGV, Segmentation fault.
  __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:120
  120     ../sysdeps/x86_64/multiarch/../strlen.S: No such file or directory.
  (gdb) bt
  #0  __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:120
  #1  0x00005555555b716b in promex_dump_listener_metrics (htx=0x5555558fadf0, appctx=0x555555926070) at contrib/prometheus-exporter/service-prometheus.c:722
  #2  promex_dump_metrics (htx=0x5555558fadf0, si=0x555555925920, appctx=0x555555926070) at contrib/prometheus-exporter/service-prometheus.c:1200
  #3  promex_appctx_handle_io (appctx=0x555555926070) at contrib/prometheus-exporter/service-prometheus.c:1477
  #4  0x00005555556f0c94 in task_run_applet (t=0x555555926180, context=0x555555926070, state=<optimized out>) at src/applet.c:88
  #5  0x00005555556bc6d8 in run_tasks_from_lists (budgets=budgets@entry=0x7fffffffe374) at src/task.c:548
  #6  0x00005555556bd1a0 in process_runnable_tasks () at src/task.c:750
  #7  0x0000555555696cdd in run_poll_loop () at src/haproxy.c:2870
  #8  0x0000555555697025 in run_thread_poll_loop (data=data@entry=0x0) at src/haproxy.c:3035
  #9  0x0000555555596c90 in main (argc=<optimized out>, argv=0x7fffffffe818) at src/haproxy.c:3723
  quit)

this bug was introduced by commit
e3f7bd5ae9e969cbfe87e4130d06bff7a3e814c6 ("MEDIUM:
contrib/prometheus-exporter: add listen stats"), which is present for
2.4 only, so no backport needed.

Signed-off-by: William Dauchy <wdauchy@gmail.com>