[Click] IPFragmenter bug (click-1.4.3)

[Eddie Kohler]

Hi Alfeiks,

When you see an error like this, it is useful in Click to look at the 
configuration first, and/or any elements you have written.  In this case, what 
is the element that precedes IPRewriter in the path?  Whatever that element 
is, it has passed a null packet pointer to "output(x).push()".  That is illegal.

Eddie


Alfeiks Kaanoken wrote:
> So, continuing the bug finding.
> I decide to do the following things to be sure for the normal backtrace -
> - I removed inline directives from element.hh (include/click/element.hh)
> - I moved all code from element.hh to the element.cc (lib/element.cc)
> and get the new ideas and things.
> I get the new bt -
> click: ../lib/ipflowid.cc:32: IPFlowID::IPFlowID(const Packet*): 
> Assertion `iph && udph && (((iph)->ip_off & (__extension__ ({ register 
> unsigned short int __v, __x = (0x1fff); if (__builtin_constant_p (__x)) 
> __v = ((((__x) >> 8) & 0xff) | (((__x) & 0xff) << 8)); else __asm__ 
> ("rorw $8, %w0" : "=r" (__v) : "0" (__x) : "cc"); __v; }))) == 0)' failed.
> 
> Program received signal SIGABRT, Aborted.
> 0x4013bd81 in kill () from /lib/libc.so.6
> (gdb) bt
> #0  0x4013bd81 in kill () from /lib/libc.so.6
> #1  0x4013bb05 in raise () from /lib/libc.so.6
> #2  0x4013d05d in abort () from /lib/libc.so.6
> #3  0x4013500f in __assert_fail () from /lib/libc.so.6
> #4  0x080f0007 in IPFlowID (this=0xbffff2e0, p=0x0) at ../lib/ipflowid.cc:32
> #5  0x080c69f3 in IPRewriter::push (this=0x8162150, port=0, p_in=0x0)
>     at ../elements/tcpudp/iprewriter.cc:292
> #6  0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166320) at 
> ../lib/element.cc:986
> #7  0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166320) at 
> ../lib/element.cc:986
> #8  0x080940e7 in IPFragmenter::fragment (this=0x8164350, p_in=0x8166240)
>     at ../elements/ip/ipfragmenter.cc:162
> #9  0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166240) at 
> ../lib/element.cc:986
> #10 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166240) at 
> ../lib/element.cc:986
> #11 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166240) at 
> ../lib/element.cc:986
> #12 0x080b82ae in PaintTee::simple_action (this=0x40227ff4, p=0x8168288)
>     at ../elements/standard/painttee.cc:50
> #13 0x080f6b25 in Element::push (this=0x8164470, p=0x8168288) at 
> ../lib/element.cc:848
> #14 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #15 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #16 0x0809fdd9 in LinearIPLookup::push (this=0x815efe0, p=0x8168288)
>     at ../elements/ip/lineariplookup.cc:304
> #17 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #18 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #19 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #20 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #21 0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8168288) at 
> ../lib/element.cc:986
> #22 0x080d2007 in FromDevice::selected (this=0x815f6f8)
>     at ../elements/userlevel/fromdevice.cc:364
> #23 0x0810d873 in Master::run_selects (this=0x815eba8, more_tasks=244) 
> at ../lib/master.cc:597
> #24 0x08101c40 in RouterThread::driver (this=0x815ec98) at 
> routerthread.hh:161
> #25 0x080e7b63 in main (argc=3, argv=0xbffff804) at master.hh:121
> 
> and I decide to look at the pointers
> (gdb) f 5
> #5  0x080c69f3 in IPRewriter::push (this=0x8162150, port=0, p_in=0x0)
>     at ../elements/tcpudp/iprewriter.cc:292
> 292       IPFlowID flow(p);
> (gdb) p p_in
> $1 = (Packet *) 0x0
> (gdb) f 6
> #6  0x080f6ee0 in Element::Port::push (this=0x40227ff4, p=0x8166320) at 
> ../lib/element.cc:986
> 986         _e->push(_port, p);
> (gdb) p p
> $2 = (Packet *) 0x8166320
> (gdb) p _e
> $4 = (Element *) 0x114d3c
> How you can see the ``_e'' pointer address is not valid.
> Now I will look for the ``Element::Port::Port(Element* owner, Element* 
> e, int p)'' calling, because I think that this creation process is going 
> without correct parameters.
> Is any other ideas ?
> 
> Thanks
>