berni at birkenwald
Jul 22, 2008, 4:26 PM
Post #1 of 1
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Segfault in freshclam (current svn trunk)
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Hi,
I am the creator of bug #715
(https://wwws.clamav.net/bugzilla/show_bug.cgi?id=715) which requested
IPv6 support in freshclam. As it got integrated in r3940 I created
custom .deb packages and installed them on both of my testhosts
* #1 Debian Lenny VM (KVM), i386
* #2 Ubuntu Hardy VM (Xen), amd64
both freshclam.conf files point to db.ipv6.clamav.net rotation.
#2 has never been upgraded and still runs r3940 without any apparent
problems. I've rebuilt the Debian packages using the current trunk
revision for #1 several times and noticed that freshclam started to
crash every now and then recently. I'm pretty sure it has started with
revision r3947 which integrated a new mirror loadbalancing code.
Here is a collection of debugging information I've sent to #clamav, I
think it's better suited here on the ML.
gdb bt (r3955): http://sial.org/pbot/31610
valgrind (r3976): http://pastebin.ca/1080097
I've tried to understand the code but I don't think it should be
happening. I've added a few debug printf-statements and it looks like
the tempname variable in freshclam/manager.c:getpatch() gets trashed, it
is fine before and when calling getfile() in manager.c:904, fine
throughout the whole getfile() function (I've added a printf right
before return there) but is trashed at the following open statement in
manager.c:912. Partial strace for this is
write(1, "Downloading daily-7743.cdiff [10"..., 36) = 36
open(0x303431, O_RDONLY) = -1 EFAULT (Bad address)
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
so it looks like something is overwriting the pointer. I'm not an
experienced C coder so I'm stuck here, maybe someone more experienced
can have a look at this.
Crashes don't happen always, I've had cases where freshclam crashed
repeatedly directly at startup, but sometimes it took a couple of hours
or even days before it crashed. But the bogus pointer 0x303431 seems to
be stable.
Regards,
Bernhard
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