On 01/16/2015 01:00 PM, Avijit Das wrote: > > >> Date: Fri, 16 Jan 2015 09:07:50 -0500 >> From: [email protected] >> To: [email protected]; [email protected] >> Subject: Re: kernel panic in selinux driver >> >> On 01/16/2015 04:24 AM, Avijit Das wrote: >> > Hi All, >> > >> > >> > >> > I am seeing kernel panic in selinux code sometime during boot up and on >> > random scenarios. Has anyone encountered similar issue. Any help in this >> > is highly appreciated. >> Those would appear to be bugs in the kernel credential handling code >> rather than in SELinux; SELinux is just the messenger. What kernel >> version are you using? > > [Avijit] I am using kernel version 3.10
I don't know if it is related, but Linux 3.10.38 includes this fix for a race in the wait code.
>From a756e3d4c71d3de28373076da2552260741f3d0d Mon Sep 17 00:00:00 2001 From: Oleg Nesterov <[email protected]> Date: Mon, 7 Apr 2014 15:38:41 -0700 Subject: [PATCH] wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE race 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 <[email protected]> Reported-by: Jan Kratochvil <[email protected]> Reported-by: Michal Schmidt <[email protected]> Tested-by: Michal Schmidt <[email protected]> Cc: Al Viro <[email protected]> Cc: Lennart Poettering <[email protected]> Cc: Roland McGrath <[email protected]> Cc: Tejun Heo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/exit.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 7bb73f9..80495a1 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -570,9 +570,6 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p, 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. @@ -580,9 +577,19 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p, 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)) { -- 1.9.3
_______________________________________________ Seandroid-list mailing list [email protected] To unsubscribe, send email to [email protected]. To get help, send an email containing "help" to [email protected].
