Re: [Openvpn-users] v2.0 hangs

[Timo Sirainen <tss@xxxxxx>]

On 6.5.2004, at 19:04, James Yonan wrote:

> Basically you have a call graph like tunnel_point_to_point -> 
> process_io ->
> process_outgoing_link -> link_socket_write -> link_socket_write_udp ->
> link_socket_write_udp_posix -> sendto
>
> I don't see any uninitialized data on first glance.  There are some 
> ASSERT
> statements though.  Does valgrind know that certain functions like 
> ASSERT or
> msg (M_FATAL, ...) might never return?

Valgrind is basically x86 CPU emulator, so it just runs the code and 
whenever it accesses memory that hasn't been initialized before (or 
points to invalid location), it gives an error. So it doesn't really 
know why it's accessed.

Could it be that there's some holes (padding?) in memory that you just 
skip instead of setting to zero?

> > > > And lots of problems inside libcrypto. I'm not sure if they're real 
> > > > or
> > > > not.
> > >
> > > These tend to look like false alarms.
> >
> > Valgrind usually shows pretty correctly if there's problems. Sometimes
> > it just reports the errors in a bit wrong place or without enough
> > information.
>
> I haven't looked in detail at the libcrypto code (essentially the 
> non-SSL part
> of OpenSSL), it's certainly worth looking at if you think the problems 
> are real.

I'm not sure about those. I get a few errors in my code too from libssl 
and haven't figured out why that's happening. It might be just that 
it's getting confused with some commands.

One thing I recently noticed was that when I had code similiar to:

int foo, bar;

bar = foo;
..
function(bar);

It complained about bar being uninitialized inside function(), not at 
"bar = foo" where it really happened. The same thing might be with 
libcrypto calls too.

Anyway, now it seems to work fine with me. After I get the rest of the 
VPN stuff working (routing/firewalling mostly) I'll go through OpenVPN 
code more throughoutly and see if I can find any (potential) problems.

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