diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2014-04-07 15:38:29 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-04-22 16:49:22 -0700 |
| commit | d143d1ed4494d606c7a08a08345ce467cf1d0dde (patch) | |
| tree | 8ec301c358a12607b5ac69a54053b52101e43384 | |
| parent | bab289853c744ba50cf58bb1568d15ceb7d207a2 (diff) | |
exit: call disassociate_ctty() before exit_task_namespaces()
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@redhat.com>
Reported-by: Sree 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/exit.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 92d7823648f..dcde2c4b61d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -790,6 +790,8 @@ 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(); @@ -805,13 +807,9 @@ 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 */ |