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| author | Oleg Nesterov <oleg@redhat.com> | 2012-01-04 17:29:20 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-04 15:01:59 -0800 |
| commit | 8a88951b5878dc475dcd841cefc767e36397d14e (patch) | |
| tree | c31fd8cdfa08dce4768f42e556d97929deac2343 /kernel/ptrace.c | |
| parent | 50b8d257486a45cba7b65ca978986ed216bbcc10 (diff) | |
| download | linux-stable-8a88951b5878dc475dcd841cefc767e36397d14e.tar.gz linux-stable-8a88951b5878dc475dcd841cefc767e36397d14e.tar.bz2 linux-stable-8a88951b5878dc475dcd841cefc767e36397d14e.zip | |
ptrace: ensure JOBCTL_STOP_SIGMASK is not zero after detach
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>
Cc: <stable@kernel.org> [3.1]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/ptrace.c')
| -rw-r--r-- | kernel/ptrace.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 24d04477b257..78ab24a7b0e4 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 |