3.4-stable patches

added patches:
	wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch

diff --git a/queue-3.4/series b/queue-3.4/series
index fd30a77c46675af8af3f6da5532b34d667972dd7..8cb1eb10531d9f48157b50c2bd93c2ab29ea0543 100644 (file)
--- a/queue-3.4/series
+++ b/queue-3.4/series
@@ -24,3 +24,4 @@ jffs2-fix-segmentation-fault-found-in-stress-test.patch
 jffs2-fix-crash-due-to-truncation-of-csize.patch
 jffs2-avoid-soft-lockup-in-jffs2_reserve_space_gc.patch
 jffs2-remove-from-wait-queue-after-schedule.patch
+wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch

diff --git a/queue-3.4/wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch b/queue-3.4/wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch
new file mode 100644 (file)
index 0000000..73ee429
--- /dev/null
+++ b/queue-3.4/wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch
@@ -0,0 +1,78 @@
+From dfccbb5e49a621c1b21a62527d61fc4305617aca Mon Sep 17 00:00:00 2001
+From: Oleg Nesterov <oleg@redhat.com>
+Date: Mon, 7 Apr 2014 15:38:41 -0700
+Subject: wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE race
+
+From: Oleg Nesterov <oleg@redhat.com>
+
+commit dfccbb5e49a621c1b21a62527d61fc4305617aca 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 50b8d257486a
+"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: Oleg Nesterov <oleg@redhat.com>
+Reported-by: Jan Kratochvil <jan.kratochvil@redhat.com>
+Reported-by: Michal Schmidt <mschmidt@redhat.com>
+Tested-by: Michal 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: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/exit.c |   15 +++++++++++----
+ 1 file changed, 11 insertions(+), 4 deletions(-)
+
+--- a/kernel/exit.c
++++ b/kernel/exit.c
+@@ -761,9 +761,6 @@ static void reparent_leader(struct task_
+                               struct list_head *dead)
+ {
+       list_move_tail(&p->sibling, &p->real_parent->children);
+-
+-      if (p->exit_state == EXIT_DEAD)
+-              return;
+       /*
+        * If this is a threaded reparent there is no need to
+        * notify anyone anything has happened.
+@@ -771,9 +768,19 @@ static void reparent_leader(struct task_
+       if (same_thread_group(p->real_parent, father))
+               return;
+ 
+-      /* We don't want people slaying init.  */
++      /*
++       * We don't want people slaying init.
++       *
++       * Note: we do this even if it is EXIT_DEAD, wait_task_zombie()
++       * can change ->exit_state to EXIT_ZOMBIE. If this is the final
++       * state, do_notify_parent() was already called and ->exit_signal
++       * doesn't matter.
++       */
+       p->exit_signal = SIGCHLD;
+ 
++      if (p->exit_state == EXIT_DEAD)
++              return;
++
+       /* If it has exited notify the new parent about this child's death. */
+       if (!p->ptrace &&
+           p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {