After chewing this problem over for a while I think libwrap is more at
fault than MySQL, but I'll fling this to the list anyway in case somebody
else has seen it before.
Whenever a client tries to connect to a MySQL server that has been denied
by the server's TCP wrappers, libwrap executes the rejection code (sends
email) then MySQL bombs with a signal 11. The surviving children need
"kill -9" and safe_mysqld doesn't restart the DB.
The workaround is to place "mysqld: ALL" in /etc/hosts.allow or,
presumably, to rebuild --without-libwrap. Here's the trace:
======================================================================
020219 16:55:03 mysqld started
020219 16:55:03 /usr/local/libexec/mysqld: Can't create/write to file
'/usr/local/var/mysql/host.pid' (Errcode: 13)
[I don't know if that's related. The directory is 0777].
/usr/local/libexec/mysqld: ready for connections
[attempt a connection from a machine that libwrap will reject]
mysqld got signal 11;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked agaist is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help diagnose
the problem, but since we have already crashed, something is definitely wrong
and this may fail
key_buffer_size=8388600
record_buffer=131072
sort_buffer=2097144
max_used_connections=4
max_connections=100
threads_connected=2
It is possible that mysqld could use up to
key_buffer_size + (record_buffer + sort_buffer)*max_connections = 225791 K
bytes of memory
Hope that's ok, if not, decrease some variables in the equation
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
Cannot determine thread, fp=0xbfffc0e0, backtrace may not be correct.
Stack range sanity check OK, backtrace follows:
0x8077e30 handle_segfault__Fi + 380
0x81226aa pthread_sighandler + 146
0x8149345 strncpy + 33
0x811e145 rfc931 + 549
(nil)
New value of fp=(nil) failed sanity check, terminating stack trace!
[...]
[ kill -9 all mysqld processes]
020219 17:00:47 mysqld ended
======================================================================
So it looks like libwrap is trying to copy a string from or to somewhere
it shouldn't. But who's fault is that? Another source of mystery is the
recent occurrence of this problem: mysqld has rejected wrapped hosts
quite happily in the past, so when it bombed I upgraded to 3.23.49 and
2.4.17. It behaves this way consistently.
My next move is to try a different libwrap, but if any of you have seen
this problem before, please let me know. Thanks!
(Slackware 8, stock 2.4.17 /usr/lib/libwrap.a 43016 bytes sum 05629 43)
--
_________________________________________________________________________
Andrew Donkin Waikato University, Hamilton, New Zealand
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