security/clamav: Segmentation fault when running clamav in a 32-bit jail on a 64-bit host

[Glen Barber]

On 8/27/10 1:32 PM, Jeremy Chadwick wrote:
>> Of course.  The new backtrace is here: http://gist.github.com/553734
> 
> I want to make sure I understand the environment -- on a native i386
> (32-bit) FreeBSD host, the software works fine.  But on a native amd64
> (64-bit) FreeBSD host, the software segfaults.  Correct?
> 

The clamav instance runs on a 64-bit host in a 32-bit jail.  In a 32-bit
host/32-bit jail environment, the software runs fine, as you suggest above.

> If so -- it appears as if the system you're providing the backtrace from
> is a 32-bit system, or within a 32-bit environment?  I would expect to
> see 64-bit addresses in the backtrace, yet they're all 32-bit.
> 
> I'm not familiar with jailed environments (or the concept/possibility of
> running a mixed-architecture jail (e.g. 64-bit host OS with 32-bit
> jails)).  I don't use lib32 on my amd64 systems.
> 

To be honest, this is the first non-base software I've had an issue with
in a mixed-arch environment.

> I did take a look at the clamav code itself (I'd have to spend a few
> hundred lines outlining it here and would rather not).  My guess is that
> there's a conflict between what the running OS architecture is and what
> the build process determines the architecture is.
> 
> Given that you have jails, and possibly a mixed architecture environment
> on a single host (e.g. 64-bit host OS with 32-bit jails), can you
> explain exactly how you go about building clamav, followed by how you go
> about running it?
> 

The build is done from ports with no special options excluding the
latest build, being:

	make -DWITH_DEBUG DEBUG_FLAGS=-g

The only make.conf entry is PERL_VERSION=5.10.1.

The clamd service runs under djb's supervise (/usr/local/sbin/clamd).
Additionally, port builds were done after setting UNAME_m and UNAME_p
[1], but I haven't had luck with that overriding the machine hardware type.

If this provides any clues, here's what file(1) sees, as well as ldd:

% file /usr/local/sbin/clamd
/usr/local/sbin/clamd: ELF 32-bit LSB executable, Intel 80386, version 1
(FreeBSD), dynamically linked (uses shared libs), for FreeBSD 8.1, not
stripped

% ldd /usr/local/sbin/clamd
/usr/local/sbin/clamd:
        libclamav.so.7 => /usr/local/lib/libclamav.so.7 (0x280ac000)
        libz.so.5 => /lib/libz.so.5 (0x281f8000)
        libbz2.so.4 => /usr/lib/libbz2.so.4 (0x2820a000)
        libm.so.5 => /lib/libm.so.5 (0x2821b000)
        libthr.so.3 => /lib/libthr.so.3 (0x28235000)
        libc.so.7 => /lib/libc.so.7 (0x2824a000)

[1] - http://www.mail-archive.com/freebsd-amd64@freebsd.org/msg00248.html

Cheers,

-- 
Glen Barber