Re: monit 4.8 segfaults on Redhat EL4

[Jan-Henrik Haukeland]

On 4. mai. 2006, at 19.16, Mike Jackson wrote:

> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 182894082848 (LWP 30022)]
> 0x0000003106b6fd00 in strlen () from /lib64/tls/libc.so.6
> (gdb) backtrace
> #0  0x0000003106b6fd00 in strlen () from /lib64/tls/libc.so.6
> #1  0x0000003106b428cc in vfprintf () from /lib64/tls/libc.so.6
> #2  0x0000003106bc1e55 in vsyslog () from /lib64/tls/libc.so.6
> #3  0x000000000040910c in log_log (priority=6, s=0x42af60 "Starting  
> %s daemon with http interface at [%s:%d]\n", ap=0x7fbffff6c0)
>    at log.c:374
> #4  0x0000000000409358 in LogInfo (s=Variable "s" is not available.
> ) at log.c:247
> #5  0x000000000040b332 in main (argc=Variable "argc" is not available.
> ) at monitor.c:460


Thank you very much for this report Mike. This trace does not make  
any sense to me though. It shows 's' with an address and then go on  
to say that s is not available. Also not having argc available for  
main() is suspicious to say the least. Does this segfault happens all  
the time or only sporadic? Do you use any special C libraries that  
you are aware of? I cannot reproduce this segfault on any Linux (SMP)  
machines I have so I wonder if you can run gdb on monit yourself and  
set a breakpoint in 'log_log' and step trough to see if anything  
strange is going on or maybe where the problem occurs. Use e.g.

$ gdb ./monit
GNU gdb Red Hat Linux (6.3.0.0-1.122rh)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and  
you are
welcome to change it and/or distribute copies of it under certain  
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for  
details.
This GDB was configured as "i386-redhat-linux-gnu"...Using host  
libthread_db library "/lib/libthread_db.so.1".

(gdb) break log_log
Breakpoint 1 at 0x804ff72: file log.c, line 362.
(gdb) run -Iv
Starting program: /home/hauk/utv/monit/monit -Iv
Reading symbols from shared object read from target memory...done.
Loaded system supplied DSO at 0x982000
[Thread debugging using libthread_db enabled]
[New Thread -1208101200 (LWP 2605)]
[Switching to Thread -1208101200 (LWP 2605)]

Breakpoint 1, log_log (priority=7,
    s=0x8080378 "%s: Debug: Adding credentials for user '%s'.\n",
    ap=0xbfeed144 "\\??H\230\233\tԽ\006\b\001") at log.c:362
362       ASSERT(s);
(gdb) n
...

> I also ran it through strace, which produces volumes of output, but  
> I won't send that unless someone needs it.

You can send the strace dump to our contact address (monitgroup at  
tildeslash.com), but try the above first.

--
Jan-Henrik Haukeland
Mobil +47 97141255