[Dovecot] imap core dumping on signal 10

[Timo Sirainen]

On Tue, 2010-07-20 at 18:53 -0400, Chris Hoogendyk wrote:
> We are just trying to bring up a new server and chose to use Dovecot 
> rather than the uw-imap from our previous servers. At this point I am 
> just testing with some throw away accounts using squirrelmail. I can 
> load my inbox, but then the imap connection is lost.

This happens always? For all users?

> Program terminated with signal 10, Bus error.

Signal 10 usually means unaligned memory access or accessing mmap()ed
file past the end of file.

> #0  0x000aa19c in mail_index_map (index=0x489, type=0) at /usr/local/src/dovecot/dovecot-1.2.12/src/lib-index//mail-index-map.c:502
> 502                     map->hdr = *hdr;
..
>         hdr = (const struct mail_index_header *) 0x8000000

This hdr alignment looks ok. Also I can't really figure out from the
code how it could be crashing here. And -O2 has optimized the backtrace
and some variables in a way that it's a bit difficult to figure out
what's actually going on.

Could you compile without -O2 (but I think -O is required or it won't
crash)? Easiest way would be to do something like:

1. cd src/lib-index/Makefile
2. Change -O2 to -O in Makefile
3. make clean && make
4. cd ../imap && make && make install

Then it would be helpful to know at least the output of:

bt full
p hdr
p *hdr
p &map->hdr
p *map->rec_map