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[John Johansen <john.johansen@xxxxxxxxxxxxx>]

** Summary changed:

- apparmor bad lock balance in during policy introspection
+ apparmor bad lock balance during policy introspection

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https://bugs.launchpad.net/bugs/1235977

Title:
  apparmor bad lock balance during policy introspection

Status in “linux” package in Ubuntu:
  In Progress
Status in “linux” source package in Saucy:
  In Progress

Bug description:
  There is a bug in the profile introspection file that results in a
  virtual root ns lock being released twice. Introspection from the root
  policy namespace is handled correctly it is only when introspection is
  done from a task in a sub policy namespace that becomes its virtual ns
  root.

  This results in the following lockdep trace
  [   78.479744] [ BUG: bad unlock balance detected! ]
  [   78.479792] 3.11.0-11-generic #17 Not tainted
  [   78.479838] -------------------------------------
  [   78.479885] grep/2223 is trying to release lock (&ns->lock) at:
  [   78.479952] [<ffffffff817bf3be>] mutex_unlock+0xe/0x10
  [   78.480002] but there are no more locks to release!
  [   78.480037] 
  [   78.480037] other info that might help us debug this:
  [   78.480037] 1 lock held by grep/2223:
  [   78.480037]  #0:  (&p->lock){+.+.+.}, at: [<ffffffff812111bd>] seq_read+0x3d/0x3d0
  [   78.480037] 
  [   78.480037] stack backtrace:
  [   78.480037] CPU: 0 PID: 2223 Comm: grep Not tainted 3.11.0-11-generic #17
  [   78.480037] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  [   78.480037]  ffffffff817bf3be ffff880007763d60 ffffffff817b97ef ffff8800189d2190
  [   78.480037]  ffff880007763d88 ffffffff810e1c6e ffff88001f044730 ffff8800189d2190
  [   78.480037]  ffffffff817bf3be ffff880007763e00 ffffffff810e5bd6 0000000724fe56b7
  [   78.480037] Call Trace:
  [   78.480037]  [<ffffffff817bf3be>] ? mutex_unlock+0xe/0x10
  [   78.480037]  [<ffffffff817b97ef>] dump_stack+0x54/0x74
  [   78.480037]  [<ffffffff810e1c6e>] print_unlock_imbalance_bug+0xee/0x100
  [   78.480037]  [<ffffffff817bf3be>] ? mutex_unlock+0xe/0x10
  [   78.480037]  [<ffffffff810e5bd6>] lock_release_non_nested+0x226/0x300
  [   78.480037]  [<ffffffff817bf2fe>] ? __mutex_unlock_slowpath+0xce/0x180
  [   78.480037]  [<ffffffff817bf3be>] ? mutex_unlock+0xe/0x10
  [   78.480037]  [<ffffffff810e5d5c>] lock_release+0xac/0x310
  [   78.480037]  [<ffffffff817bf2b3>] __mutex_unlock_slowpath+0x83/0x180
  [   78.480037]  [<ffffffff817bf3be>] mutex_unlock+0xe/0x10
  [   78.480037]  [<ffffffff81376c91>] p_stop+0x51/0x90
  [   78.480037]  [<ffffffff81211408>] seq_read+0x288/0x3d0
  [   78.480037]  [<ffffffff811e9d9e>] vfs_read+0x9e/0x170
  [   78.480037]  [<ffffffff811ea8cc>] SyS_read+0x4c/0xa0
  [   78.480037]  [<ffffffff817ccc9d>] system_call_fastpath+0x1a/0x1f

  Requires:
    user of policy namespaces
    root process with in alternate policy namespace reading the /sys/kernel/security/apparmor/profiles file

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