Hi
I?m using 4.3.30 and I?m experiencing core dumps on some servers using the directory directive in hosts.cfg. The contents of my directory sometimes change and this sometimes leads to a core dump.
In hosts.cfg I have:
directory /home/xymon/server/etc/include_xxxxx/xxxxx/
this directory contains one file per host which contain something like this: 0.0.0.0 a_unique_name # noconn NOCOLUMNS:conn,info,trends nonongreen
A cron job adds/removes files from this directory periodically, however, the directory should contain at least one file at all times.
It?s been a long time since I did any C but I think I?ve been able to track this down a bit with gdb and --debug on xymond. Here?s some xymond debug output:
5315 2021-11-03 12:08:45.037113 File /home/xymon/server/etc/include_xxxxx/xxxxx//xxxxxxxxx new timestamp 16223 2021-11-03 12:08:45.037136 -> save_checkpoint 5315 2021-11-03 12:08:45.037218 Opening file /home/xymon/server/etc/hosts.cfg 5315 2021-11-03 12:08:45.040573 Opening file /home/xymon/server/etc/include_xxxxx/xxxxx//xxxxxxxxxx .. (opens all the files) 5315 2021-11-03 12:08:45.047109 -> handle_dropnrename 5315 2021-11-03 12:08:45.047128 -> posttochannel 5315 2021-11-03 12:08:45.047144 Posting message 13651 to 1 readers 5315 2021-11-03 12:08:45.047155 <- posttochannel 5315 2021-11-03 12:08:45.047159 -> posttochannel 5315 2021-11-03 12:08:45.047168 Posting message 4683 to 1 readers 5315 2021-11-03 12:08:45.047176 <- posttochannel 5315 2021-11-03 12:08:45.047179 -> posttochannel 5315 2021-11-03 12:08:45.047188 Posting message 1367 to 1 readers 5315 2021-11-03 12:08:45.047195 <- posttochannel 5315 2021-11-03 12:08:45.047199 -> posttochannel 5315 2021-11-03 12:08:45.047207 Posting message 1905 to 1 readers 5315 2021-11-03 12:08:45.047214 <- posttochannel 5315 2021-11-03 12:08:45.047218 -> posttochannel 5315 2021-11-03 12:08:45.047221 Dropping message - no readers 5315 2021-11-03 12:08:45.047225 -> posttochannel 5315 2021-11-03 12:08:45.047228 Dropping message - no readers 5315 2021-11-03 12:08:45.047232 -> posttochannel 5315 2021-11-03 12:08:45.047240 Posting message 785 to 1 readers 5315 2021-11-03 12:08:45.047247 <- posttochannel 5315 2021-11-03 12:08:45.047251 -> posttochannel 5315 2021-11-03 12:08:45.047259 Posting message 6 to 1 readers 5315 2021-11-03 12:08:45.047266 <- posttochannel 5315 2021-11-03 12:08:45.047269 -> posttochannel 5315 2021-11-03 12:08:45.047273 Dropping message - no readers 5315 2021-11-03 12:08:45.047287 -> free_log_t 5315 2021-11-03 12:08:45.047300 <- free_log_t 5315 2021-11-03 12:08:45.047308 <- handle_dropnrename 5315 2021-11-03 12:08:45.047312 -> handle_dropnrename 16223 2021-11-03 12:08:45.240284 <- save_checkpoint 2021-11-03 12:09:00.061085 Whoops ! Failed to send message (timeout) 2021-11-03 12:09:00.061303 ->
On the last handle_dropnrename, the core dump occurs:
Program terminated with signal 6, Aborted. #0 0x00007f39f751e387 in __GI_raise (sig=sig at entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55 55 return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig); (gdb) bt #0 0x00007f39f751e387 in __GI_raise (sig=sig at entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55 #1 0x00007f39f751fa78 in __GI_abort () at abort.c:90 #2 0x0000000000415f63 in sigsegv_handler (signum=<optimized out>) at sig.c:57 #3 <signal handler called> #4 __strlen_sse2_pminub () at ../sysdeps/x86_64/multiarch/strlen-sse2-pminub.S:38 #5 0x000000000040a5ac in handle_dropnrename (cmd=cmd at entry=CMD_DROPSTATE, sender=sender at entry=0x425e3c "xymond", hostname=0x0, n1=n1 at entry=0x0, n2=n2 at entry=0x0) at xymond.c:2511 #6 0x0000000000403eb1 in main (argc=<optimized out>, argv=<optimized out>) at xymond.c:5702
What is interesting is that handle_dropnrename appears to be passed an empty hostname or null pointer if I understand gdb correctly.
In handle_dropnrename strlen is called on hostname and I think this causes the core dump? (xymond.c line 2511):
char *msgbuf = (char *)malloc(20 + strlen(hostname) + (n1 ? strlen(n1) : 0) + (n2 ? strlen(n2) : 0))I _think_ handle_dropnrename is being called around line 5700 of xymond.c:
else if (hostinfo(hwalk->hostname) == NULL) {
/* Remove all state info about this host. This will NOT remove files. */
handle_dropnrename(CMD_DROPSTATE, "xymond", hwalk->hostname, NULL, NULL);What am I doing wrong ?
Thanks
Zak
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