This is a note to let you know that I've just added the patch titled
exit: call disassociate_ctty() before exit_task_namespaces()
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
exit-call-disassociate_ctty-before-exit_task_namespaces.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c39df5fa37b0623589508c95515b4aa1531c524e Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Mon, 7 Apr 2014 15:38:29 -0700
Subject: exit: call disassociate_ctty() before exit_task_namespaces()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit c39df5fa37b0623589508c95515b4aa1531c524e upstream.
Commit 8aac62706ada ("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: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Sree Harsha Totakura <sreeharsha@xxxxxxxxxxx>
Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Cc: Sree Harsha Totakura <sreeharsha@xxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Andrey Vagin <avagin@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -791,6 +791,8 @@ void do_exit(long code)
exit_shm(tsk);
exit_files(tsk);
exit_fs(tsk);
+ if (group_dead)
+ disassociate_ctty(1);
exit_task_namespaces(tsk);
exit_task_work(tsk);
check_stack_usage();
@@ -806,13 +808,9 @@ void do_exit(long code)
cgroup_exit(tsk, 1);
- if (group_dead)
- disassociate_ctty(1);
-
module_put(task_thread_info(tsk)->exec_domain->module);
proc_exit_connector(tsk);
-
/*
* FIXME: do that only when needed, using sched_exit tracepoint
*/
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.14/wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch
queue-3.14/pid_namespace-pidns_get-should-check-task_active_pid_ns-null.patch
queue-3.14/exit-call-disassociate_ctty-before-exit_task_namespaces.patch
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