[Bug 1274720] Re: [SRU] screen server process can be crashed by byobu

[Dustin Kirkland ]

** Description changed:

  screen crashed with SIGSEGV
  
  ProblemType: Crash
  DistroRelease: Ubuntu 14.04
  Package: screen 4.1.0~20120320gitdb59704-9
  ProcVersionSignature: Ubuntu 3.13.0-5.20-generic 3.13.0
  Uname: Linux 3.13.0-5-generic x86_64
  NonfreeKernelModules: openafs
  ApportVersion: 2.13.2-0ubuntu2
  Architecture: amd64
  CurrentDesktop: GNOME
  Date: Wed Jan 29 23:59:55 2014
  ExecutablePath: /usr/bin/screen
  InstallationDate: Installed on 2010-12-05 (1152 days ago)
  InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20101202)
  ProcCmdline: SCREEN
  SegvAnalysis:
-  Segfault happened at: 0x7f4f000a1f15 <__GI_tcsetattr+117>:	mov    (%r8),%eax
-  PC (0x7f4f000a1f15) ok
-  source "(%r8)" (0x00001430) not located in a known VMA region (needed readable region)!
-  destination "%eax" ok
+  Segfault happened at: 0x7f4f000a1f15 <__GI_tcsetattr+117>:	mov    (%r8),%eax
+  PC (0x7f4f000a1f15) ok
+  source "(%r8)" (0x00001430) not located in a known VMA region (needed readable region)!
+  destination "%eax" ok
  SegvReason: reading NULL VMA
  Signal: 11
  SourcePackage: screen
  StacktraceTop:
-  ?? ()
-  ?? ()
-  ?? ()
-  ?? ()
-  ?? ()
+  ?? ()
+  ?? ()
+  ?? ()
+  ?? ()
+  ?? ()
  Title: screen crashed with SIGSEGV
  UpgradeStatus: Upgraded to trusty on 2013-10-31 (91 days ago)
  UserGroups:
+ 
+ [Impact] 
+  * Byobu users of the byobu-screen backend will find their screen process crashed, if they hit ctrl-a (screen's default escape sequence).  This is a critical breakage for byobu-screen users.
+ [Test Case]
+  * From a new or fresh Trusty installation (desktop or server), drop to a command line, and run 'byobu-screen'.  You'll be interactively prompted to choose whether ctrl-a should be handled like screen or emacs.  Choose (1) for screen.  Your screen session is now crashed.
+  * Upgrade to the package in trusty-proposed, launch a new byobu-screen session, and press ctrl-a-c to create a new window, and then ctrl-a-n and ctrl-a-p and that should all work perfectly well now.
+ [Regression Potential] 
+  * This fix does revert the change that was intended to fix a far more minor Bug: #814172.  I have reopened that bug, will fix it separately, and upload another SRU later.
+  * Otherwise, regression potential should be minimal.  Once that recent commit was reverted, the code looks very much like it's looked for a very long, stable time.
+ [Other Info]
+  * None

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https://bugs.launchpad.net/bugs/1274720

Title:
  [SRU] screen server process can be crashed by byobu

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