enterprise-support team mailing list archive

[Ian Wienand <iwienand@xxxxxxxxxx>]

Public bug reported:

We have seen consistent but infrequent segfaults of apache on a trusty
production server with 2.4.7-1ubuntu4.13 (for more examples, see [1])

---
Oct  2 19:01:03 static kernel: [8029151.932468] apache2[10642]: segfault at 7fac797803a8 ip 00007fac90b345e0 sp 00007fac84ff8e20 error 6 in mod_mpm_event.so[7fac90b2e000+d000]
---

Taking the ip - base seems to put us at a consistent offset

---
(gdb) p/x 0x7fac90b345e0 - 0x7fac90b2e000
$1 = 0x65e0

$ addr2line -e ./mod_mpm_event.so  0x65e0
/build/apache2-Rau9Dr/apache2-2.4.7/server/mpm/event/event.c:1064
---

which is at the bottom of process_socket(), which looks like

---
  1058      /*
  1059       * Prevent this connection from writing to our connection state after it
  1060       * is no longer associated with this thread. This would happen if the EOR
  1061       * bucket is destroyed from the listener thread due to a connection abort
  1062       * or timeout.
  1063       */
  1064      c->sbh = NULL;
  1065      return;
  1066  }
---

1064 seems at least plausible as a faulting location...

Some digging through httpd history reveals that this assignment was
removed on the 2.4 branch with commit [2], which seems to be largely
based on [3].  Things have been shuffled around so much it's hard to
tell exactly what might have avoided us going down this path.  Even so
I'm honestly not sure how to reproduce it -- on a fairly busy server
it's seen at most a few times a day.

[1] http://paste.openstack.org/show/584330/
[2] https://github.com/apache/httpd/commit/043eba1a0a190829c073d9ef084358f6693dbbd2
[3] https://github.com/apache/httpd/commit/285e67883e396f97dc3aad50d9dc345f15220827

** Affects: apache2 (Ubuntu)
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Ubuntu
Server/Client Support Team, which is subscribed to apache2 in Ubuntu.
Matching subscriptions: Ubuntu Server/Client Support Team
https://bugs.launchpad.net/bugs/1630413

Title:
  segfault in server/mpm/event/event.c:process_socket

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/1630413/+subscriptions