[Bug 553745]

[Rstrode]

Hi,

(In reply to comment #2)
> I think I've worked out what is going on here (and which caused me to
> raise the erroneous bug 42285):
great!

> In ply_event_loop_process_pending_events(),
> ply_event_loop_handle_timeouts() is being called *after* epoll_wait(),
> but ply_event_loop_handle_timeouts() may free event sources.
ah ha.  So to be a little more specific, a timeout callback may call ply_event_loop_stop_watching_fd and if that fd became ready at the same time as the callback then crash would result.
 
> I can reliabily force plymouthd to SIGSEGV (in various parts of the
> code) by running the following:
> 
>   plymouth show-splash
>   plymouth quit
In this case plymouth quit queues a callback to get called after the animation gets to an idle state, on_boot_splash_idle calls functions that ultimately stops watching the terminal fd.  if that callback happens in the same iteration of the loop that the terminal fd becomes ready, then boom. Makes sense. Thanks for figuring this out.

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https://bugs.launchpad.net/bugs/553745

Title:
  plymouthd crashed with SIGSEGV in
  ply_event_loop_process_pending_events()

Status in The Plymouth splash screen:
  Fix Released
Status in “plymouth” package in Ubuntu:
  Fix Released
Status in “plymouth” source package in Lucid:
  Triaged
Status in “plymouth” source package in Maverick:
  Invalid
Status in “plymouth” source package in Natty:
  Fix Released
Status in “plymouth” source package in Oneiric:
  Incomplete
Status in “plymouth” source package in Precise:
  Fix Released

Bug description:
  Binary package hint: plymouth

  just upgraded to lucid, first reboot tried to start accounts

  ProblemType: Crash
  DistroRelease: Ubuntu 10.04
  Package: plymouth 0.8.1-4
  ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
  Uname: Linux 2.6.32-19-generic i686
  NonfreeKernelModules: wl
  Architecture: i386
  Date: Thu Apr  1 22:14:11 2010
  DefaultPlymouth: /lib/plymouth/themes/kubuntu-logo/kubuntu-logo.plymouth
  ExecutablePath: /sbin/plymouthd
  MachineType: Dell Inc. Inspiron 1545
  ProcCmdLine: root=UUID=73530dc8-e3cc-4147-b801-4725b2f88141 ro quiet splash vga=792
  ProcCmdline: /sbin/plymouthd --mode=boot --attach-to-session
  ProcEnviron: PATH=(custom, no user)
  ProcFB: 0 inteldrmfb
  SegvAnalysis:
   Segfault happened at: 0xfb5fe1 <ply_event_loop_process_pending_events+513>: test   %eax,0x4(%esi)
   PC (0x00fb5fe1) ok
   source "%eax" ok
   destination "0x4(%esi)" (0x00000004) not located in a known VMA region (needed writable region)!
  SegvReason: writing NULL VMA
  Signal: 11
  SourcePackage: plymouth
  StacktraceTop:
   ply_event_loop_process_pending_events ()
   ply_event_loop_run () from /lib/libply.so.2
   ?? ()
   __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
   ?? ()
  TextPlymouth: /lib/plymouth/themes/ubuntu-text/ubuntu-text.plymouth
  Title: plymouthd crashed with SIGSEGV in ply_event_loop_process_pending_events()
  UserGroups:
   
  dmi.bios.date: 07/17/2009
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A10
  dmi.board.name: 0G848F
  dmi.board.vendor: Dell Inc.
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA10:bd07/17/2009:svnDellInc.:pnInspiron1545:pvr:rvnDellInc.:rn0G848F:rvr:cvnDellInc.:ct8:cvr:
  dmi.product.name: Inspiron 1545
  dmi.sys.vendor: Dell Inc.

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