[ovs-discuss] Crash in openvswitch 2.0.2

James Page james.page at ubuntu.com
Mon Apr 20 15:23:35 UTC 2015


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Hi Marco

Not ignoring you - just a bit busy with Ubuntu 15.04 release at the
moment - so apologies for any lag.

On 16/04/15 21:13, Marco Kuendig wrote:
> #2  0x0000000000460cd2 in format_odp_key_attr
> (a=a at entry=0x19798d4, ma=ma at entry=0x0, ds=ds at entry=0x7ffc6c10bd10,
> verbose=verbose at entry=true) at ../lib/odp-util.c:1332

The thing that has us puzzled is why at this point in the stack is the
automatic variable 'is_exact' not true:

    case OVS_KEY_ATTR_UNSPEC:
    case __OVS_KEY_ATTR_MAX:
    default:
        format_generic_odp_key(a, ds);
        if (!is_exact) {
            ds_put_char(ds, '/');
            format_generic_odp_key(ma, ds);
        }
        break;
    }

As the 'ma' parameter is 0, this should mean that is_exact follows:

    is_exact = ma ? odp_mask_attr_is_exact(ma) : true;

and as ma == 0 then is_exact should == true.  But for some reason its no
t.

As you see this with the un-optimized package, we can't blame the
optimizer - so something else must be happening - maybe an overflow?

That would have to happen in L952->L978 so not a huge amount of scope.

It might be good to see if we can determine whether namebuf is the
culprit.

- -- 
James Page
Ubuntu and Debian Developer
james.page at ubuntu.com
jamespage at debian.org
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