[ovs-discuss] Crash in openvswitch 2.0.2

[James Page]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Hi Joe

On 09/05/15 00:00, Joe Stringer wrote:
> I wonder if this patch fixes the issue: 
> https://github.com/openvswitch/ovs/commit/546953509095cec6fad42663b659
171618b765d2
>
>  Note that the last three lines within the bad_key_len /
> bad_mask_len conditional statement are the following:
> 
> format_generic_odp_key(ma, ds); ds_put_char(ds, ')'); return;
> 
> This is the same logic as the end of the function, where the
> backtrace is reporting the callstack to be. Jarno pointed out that
> the compiler could optimize out the first copy of this code to turn
> into a jump instruction which jumps inside the if (!is_exact)
> statement. Hence the backtrace shows this confusing callstack.
> 
> Note that this problem would only present itself if there is: A) A
> mismatch between a newer kernel version and an older userspace 
> (OVS<2.3), where B) The kernel has a new flow match field available
> which ovs-vswitchd doesn't understand, and C) A flow_del command
> fails for some reason.
> 
> It would be great if we could confirm by getting the existing build
> of OVS and applying the patch above.

Actually that's really interesting - once I actually managed to get
the unoptimized build sorted out correctly, we hit this particular
issue in our test OpenStack cloud within a couple of days - I picked
the commit you detailed above into the PPA at that point in time, and
we've not seen a crash since.

I'd assumed it was something new - but your analysis would point to
the source of the problem.

Marco - have you seen any recurrence of this issue with the PPA packages
?

I'll get this picked and uploaded as a stable update today.

Cheers

James

- -- 
James Page
Ubuntu and Debian Developer
james.page at ubuntu.com
jamespage at debian.org
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=bBZ9
-----END PGP SIGNATURE-----