[tor-bugs] #6341 [Tor Relay]: "if (circ != conn->active_circuits)" in connection_or_flush_from_first_active_circuit() is wrong?

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#6341: "if (circ != conn->active_circuits)" in
connection_or_flush_from_first_active_circuit() is wrong?
-----------------------+----------------------------------------------------
 Reporter:  arma       |          Owner:     
     Type:  defect     |         Status:  new
 Priority:  normal     |      Milestone:     
Component:  Tor Relay  |        Version:     
 Keywords:             |         Parent:     
   Points:             |   Actualpoints:     
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 Here are our cryptic hints:

 {{{
 connection_or_flush_from_first_active_circuit(): "if (circ !=
 conn->active_circuits)" is wrong, especialy with ewma. read comments, that
 means it show how stuff is broken.

 that means random crashes for "connection_write_to_buf(NULL->body" if ewma
 enabled.

 just remove that condition block, no need any goto before every stream
 started reads and all circs with empty queue marked as inactive.

 "&& queue->head" saves from crashes, but that condition is wrong anyway.
 you can't unblock streams when you need it.

 why need "re-add the cell_ewma_t" inside for{} ? what purpose for{} if you
 never can flush more than 1 cell for ewma anyway? Why there are no
 consistent logic for just one small func?
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6341>
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