Re: [Lurker-users] SIGBUS in mbox.c (CVS 20030409)

[Wesley W. T. <we...@te...>]

On Fri, Apr 11, 2003 at 12:49:24PM +0800, Federico Sevilla III wrote:
> Using a copy checked out from CVS on 2003-04-09, I hit SIGBUS in mbox.c
> during a database rebuild from scratch. I hope the backtrace helps fix
> things. If you need more information please let me know.

I need some more information. :-)

> (gdb) run -n
> Starting program: /usr/sbin/lurkerd -n
> 
> Program received signal SIGBUS, Bus error.
> 0x08052dcf in my_mbox_find_special (k=0x806bccd "\nFrom ", s=0x42b0a22c "", e=0x42b0b22c "") at mbox.c:220
> 220     mbox.c: Permission denied.
>         in mbox.c
> (gdb) bt
> #0  0x08052dcf in my_mbox_find_special (k=0x806bccd "\nFrom ", s=0x42b0a22c "", e=0x42b0b22c "") at mbox.c:220
> #1  0x08054654 in lu_mbox_map_message (mbox=0x8073c48, msg=0x4124d920, start=25938120) at mbox.c:1072
> #2  0x08057fe7 in my_service_mbox (h=0x4124d9c0, request=0x4124da05 "m0u...@bi...", ext=0x4124da24 "txt") at service.c:1356
> #3  0x0805b193 in lu_service_connection (fd=0x80b9a00) at service.c:2666
> #4  0x0805caa2 in my_main_handle_client (arg=0x80b9a00) at main.c:137
> #5  0x40019b02 in st_thread_create () from /usr/lib/libst.so.1
> #6  0x000f4240 in ?? ()

This SIGBUS occured while you were opening a message in the browser,
correct? So, it was mid-import and you viewed a message. This should be
ok...

Judging by the code in that region, it has somehow tried to access memory
past the end of the mmap'd mbox. This is odd since I keep a pointer to the
end of the mmap/eof.

If possible, I would love to know the value of variables: 
	s, e in my_mbox_find_special
	start, amt, buf, e, msg->map.size, msg->map.off in lu_mbox_map_message
... at the point of the crash.

I just commited a bit of caution in cvs. I am hoping to have it assert fail
a little earlier so that I can be certain where things are going wrong.
After you get those variables, try the latest cvs and see if it asserts.

---
Wes