1. 06 May, 2014 37 commits
  2. 27 Apr, 2014 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.10.38 · bdec4322
      Greg Kroah-Hartman authored
      bdec4322
    • Oleg Nesterov's avatar
      exit: call disassociate_ctty() before exit_task_namespaces() · 16739781
      Oleg Nesterov authored
      commit c39df5fa upstream.
      
      Commit 8aac6270 ("move exit_task_namespaces() outside of
      exit_notify()") breaks pppd and the exiting service crashes the kernel:
      
          BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
          IP: ppp_register_channel+0x13/0x20 [ppp_generic]
          Call Trace:
            ppp_asynctty_open+0x12b/0x170 [ppp_async]
            tty_ldisc_open.isra.2+0x27/0x60
            tty_ldisc_hangup+0x1e3/0x220
            __tty_hangup+0x2c4/0x440
            disassociate_ctty+0x61/0x270
            do_exit+0x7f2/0xa50
      
      ppp_register_channel() needs ->net_ns and current->nsproxy == NULL.
      
      Move disassociate_ctty() before exit_task_namespaces(), it doesn't make
      sense to delay it after perf_event_exit_task() or cgroup_exit().
      
      This also allows to use task_work_add() inside the (nontrivial) code
      paths in disassociate_ctty().
      
      Investigated by Peter Hurley.
      Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
      Reported-by: default avatarSree Harsha Totakura <sreeharsha@totakura.in>
      Cc: Peter Hurley <peter@hurleysoftware.com>
      Cc: Sree Harsha Totakura <sreeharsha@totakura.in>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Cc: Jeff Dike <jdike@addtoit.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Andrey Vagin <avagin@openvz.org>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      16739781
    • Oleg Nesterov's avatar
      wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE race · a756e3d4
      Oleg Nesterov authored
      commit dfccbb5e upstream.
      
      wait_task_zombie() first does EXIT_ZOMBIE->EXIT_DEAD transition and
      drops tasklist_lock.  If this task is not the natural child and it is
      traced, we change its state back to EXIT_ZOMBIE for ->real_parent.
      
      The last transition is racy, this is even documented in 50b8d257
      "ptrace: partially fix the do_wait(WEXITED) vs EXIT_DEAD->EXIT_ZOMBIE
      race".  wait_consider_task() tries to detect this transition and clear
      ->notask_error but we can't rely on ptrace_reparented(), debugger can
      exit and do ptrace_unlink() before its sub-thread sets EXIT_ZOMBIE.
      
      And there is another problem which were missed before: this transition
      can also race with reparent_leader() which doesn't reset >exit_signal if
      EXIT_DEAD, assuming that this task must be reaped by someone else.  So
      the tracee can be re-parented with ->exit_signal != SIGCHLD, and if
      /sbin/init doesn't use __WALL it becomes unreapable.
      
      Change reparent_leader() to update ->exit_signal even if EXIT_DEAD.
      Note: this is the simple temporary hack for -stable, it doesn't try to
      solve all problems, it will be reverted by the next changes.
      Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
      Reported-by: default avatarJan Kratochvil <jan.kratochvil@redhat.com>
      Reported-by: default avatarMichal Schmidt <mschmidt@redhat.com>
      Tested-by: default avatarMichal Schmidt <mschmidt@redhat.com>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Lennart Poettering <lpoetter@redhat.com>
      Cc: Roland McGrath <roland@hack.frob.com>
      Cc: Tejun Heo <tj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a756e3d4