[tor-bugs] #5645 [Tor Client]: rend_mid_rendezvous() encodes rendezvous cookie before checking for proto violation

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#5645: rend_mid_rendezvous() encodes rendezvous cookie before checking for proto
violation
------------------------+---------------------------------------------------
 Reporter:  asn         |          Owner:                    
     Type:  defect      |         Status:  new               
 Priority:  normal      |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Client  |        Version:                    
 Keywords:              |         Parent:  #5643             
   Points:              |   Actualpoints:                    
------------------------+---------------------------------------------------
 {{{
 rend_mid_rendezvous(or_circuit_t *circ, const uint8_t *request,
                     size_t request_len)
 {
   or_circuit_t *rend_circ;
   char hexid[9];
   int reason = END_CIRC_REASON_INTERNAL;
   base16_encode(hexid,9,(char*)request,request_len<4?request_len:4);

   if (request_len>=4) {
     log_info(LD_REND,
              "Got request for rendezvous from circuit %d to cookie %s.",
              circ->p_circ_id, hexid);
   }
 }}}

 [censored] found this:
 {{{
 rend_mid_rendezvous() fun. why need decode before protocol violation
 checks.
 }}}

 It doesn't seem exploitable but it would be good to do everything after
 the proto violation checks are done.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5645>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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