diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2012-01-04 17:29:20 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-06 14:17:34 -0800 |
| commit | 2c60e18b07e8e08c7e3b6cc8288b0e04e18844f7 (patch) | |
| tree | df8b16065898d83dde5dc78149990bbf90486c0c | |
| parent | 9e83ca1fcff0eee2ea7ef2508de95691a0cdeb0c (diff) | |
ptrace: ensure JOBCTL_STOP_SIGMASK is not zero after detach
commit 8a88951b5878dc475dcd841cefc767e36397d14e upstream.
This is the temporary simple fix for 3.2, we need more changes in this
area.
1. do_signal_stop() assumes that the running untraced thread in the
stopped thread group is not possible. This was our goal but it is
not yet achieved: a stopped-but-resumed tracee can clone the running
thread which can initiate another group-stop.
Remove WARN_ON_ONCE(!current->ptrace).
2. A new thread always starts with ->jobctl = 0. If it is auto-attached
and this group is stopped, __ptrace_unlink() sets JOBCTL_STOP_PENDING
but JOBCTL_STOP_SIGMASK part is zero, this triggers WANR_ON(!signr)
in do_jobctl_trap() if another debugger attaches.
Change __ptrace_unlink() to set the artificial SIGSTOP for report.
Alternatively we could change ptrace_init_task() to copy signr from
current, but this means we can copy it for no reason and hide the
possible similar problems.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | kernel/ptrace.c | 13 | ||||
| -rw-r--r-- | kernel/signal.c | 2 |
2 files changed, 12 insertions, 3 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index a70d2a5d8c7b..67d1fdd3c553 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -96,9 +96,20 @@ void __ptrace_unlink(struct task_struct *child) */ if (!(child->flags & PF_EXITING) && (child->signal->flags & SIGNAL_STOP_STOPPED || - child->signal->group_stop_count)) + child->signal->group_stop_count)) { child->jobctl |= JOBCTL_STOP_PENDING; + /* + * This is only possible if this thread was cloned by the + * traced task running in the stopped group, set the signal + * for the future reports. + * FIXME: we should change ptrace_init_task() to handle this + * case. + */ + if (!(child->jobctl & JOBCTL_STOP_SIGMASK)) + child->jobctl |= SIGSTOP; + } + /* * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick * @child in the butt. Note that @resume should be used iff @child diff --git a/kernel/signal.c b/kernel/signal.c index 291c9700be75..195331c56ad3 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1986,8 +1986,6 @@ static bool do_signal_stop(int signr) */ if (!(sig->flags & SIGNAL_STOP_STOPPED)) sig->group_exit_code = signr; - else - WARN_ON_ONCE(!current->ptrace); sig->group_stop_count = 0; |