Re: Double-free bug

[Will Bryant]

Hi Martin,

I get it using the monitrc that's in CVS - I just have to build and run under Ubuntu edgy's glibc.

Cheers,
Will

On 12/22/06, Martin Pala <address@hidden> wrote:

Thanks for report :)

I tried to replicate the problem without success (yet), can you send the
monit configuration?

Thanks,
Martin

Will Bryant wrote:
> I discovered I can consistently provoke problems by commenting out all
> services in the config file, and simply starting monit on my ubuntu desktop.
>
> To get a better backtrace I turned -O2 off and rebuilt so the functions
> weren't inlined:
>
> #0  0xffffe410 in __kernel_vsyscall ()
> #1  0xb7c1a770 in raise () from /lib/tls/i686/cmov/libc.so.6
> #2  0xb7c1bef3 in abort () from /lib/tls/i686/cmov/libc.so.6
> #3  0xb7c4fd0b in __fsetlocking () from /lib/tls/i686/cmov/libc.so.6
> #4  0xb7c578bd in mallopt () from /lib/tls/i686/cmov/libc.so.6
> #5  0xb7c57a44 in free () from /lib/tls/i686/cmov/libc.so.6
> #6  0x0805095a in _gc_inf (i=0x80c4328) at gc.c:427
> #7  0x0804fe88 in _gc_service (s=0x80a24f4) at gc.c:173
> #8  0x0804fda3 in _gc_service_list (s=0x80a24f4) at gc.c:148
> #9  0x0804fb38 in gc () at gc.c:92
> #10 0x08053b29 in do_exit () at monitor.c:442
> #11 0x08053421 in main (argc=1244508, argv=0xb7d25000) at monitor.c:120
>
> Nothing else calls _gc_inf, so this may just be where glibc happens to
> notice the heap corruption caused by an earlier double-free.
>
> Will
>
>
> On 12/21/06, * Will Bryant* <address@hidden
> <mailto: address@hidden>> wrote:
>
>     Hi guys,
>
>     I eventually managed to reproduce the double-free bug I mentioned on
>     the general list, which happened on one of my production servers and
>     more or less knocked it over.  Here's the stack trace:
>
>     #0  0xffffe410 in __kernel_vsyscall ()
>     #1  0xb7ca1770 in raise () from /lib/tls/i686/cmov/libc.so.6
>     #2  0xb7ca2ef3 in abort () from /lib/tls/i686/cmov/libc.so.6
>     #3  0xb7cd6d0b in __fsetlocking () from /lib/tls/i686/cmov/libc.so.6
>     #4  0xb7cdf1cd in free () from /lib/tls/i686/cmov/libc.so.6
>     #5  0xb7ce053e in calloc () from /lib/tls/i686/cmov/libc.so.6
>     #6  0x08060d18 in xcalloc (count=1, nbytes=16) at xmalloc.c:93
>     #7  0x0806d6f2 in addeventaction (_ea=0x80ad5a0, failed=1, passed=1)
>     at p.y:2334
>     #8  0x0806dc77 in createservice (type=3, name=0x811b308 "renderd",
>     value=0x80e6260 "/var/run/modellure/renderd.pid",
>         check=0x805f010 <check_process>) at p.y:1799
>     #9  0x08071909 in yyparse () at p.y:705
>     #10 0x08071e3a in parse (controlfile=0x8098410 "/etc/monit/monitrc")
>     at p.y:1633
>     #11 0x080525d4 in main (argc=7, argv=0xbfbd9614) at monitor.c:225
>
>     Is that enough info to diagnose the problem?  It looks to me like it
>     could just be due to an uninitialized structure, but I don't
>     understand enough of the code yet to say.
>
>     Will
>
>
>
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>
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