[tor-bugs] #17752 [Tor]: Null pointer deref in connection_ap_attach_pending()

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#17752: Null pointer deref in connection_ap_attach_pending()
-------------------------------------+------------------------------------
 Reporter:  dgoulet                  |          Owner:
     Type:  defect                   |         Status:  needs_revision
 Priority:  Very High                |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor                      |        Version:  Tor: unspecified
 Severity:  Major                    |     Resolution:
 Keywords:  crash TorCoreTeam201512  |  Actual Points:
Parent ID:                           |         Points:
  Sponsor:                           |
-------------------------------------+------------------------------------
Changes (by dgoulet):

 * status:  needs_information => needs_revision


Comment:

 New stack trace. I can reproduce that reliably every time I disconnect
 from my VPN and try to connect to an HS after that:

 {{{
 Dec 17 16:13:58.000 [notice] Our IP address has changed.  Rotating keys...
 Dec 17 16:13:58.000 [notice] Tor now sees network activity. Restoring
 circuit build timeout recording. Network was down for 184 seconds during
 131 circuit attempts.
 Dec 17 16:14:05.000 [err] tor_assertion_failed_(): Bug:
 src/or/connection_edge.c:806: connection_ap_attach_pending: Assertion conn
 && entry_conn failed; aborting. (on Tor 0.2.8.0-alpha-dev
 b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug: Assertion conn && entry_conn failed in
 connection_ap_attach_pending at src/or/connection_edge.c:806. Stack trace:
 (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(log_backtrace+0x42)
 [0x564effb77d42] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:
 /usr/local/bin/tor(tor_assertion_failed_+0x8d) [0x564effb85fcd] (on Tor
 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:
 /usr/local/bin/tor(connection_ap_attach_pending+0x109) [0x564effb2eb19]
 (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:
 /usr/local/bin/tor(circuit_build_needed_circs+0x38) [0x564effb0e4d8] (on
 Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(+0x3c118)
 [0x564effa84118] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/lib/x86_64-linux-
 gnu/libevent-2.0.so.5(event_base_loop+0x7fc) [0x7f1bde6dea0c] (on Tor
 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(do_main_loop+0x20d)
 [0x564effa84b5d] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(tor_main+0x19ad)
 [0x564effa880cd] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(main+0x19)
 [0x564effa80949] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /lib/x86_64-linux-
 gnu/libc.so.6(__libc_start_main+0xf0) [0x7f1bdda5da00] (on Tor 0.2.8.0
 -alpha-dev b9714e1366a19dff)
 Dec 17 16:14:05.000 [err] Bug:     /usr/local/bin/tor(_start+0x29)
 [0x564effa80999] (on Tor 0.2.8.0-alpha-dev b9714e1366a19dff)
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17752#comment:6>
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