• Oleg Nesterov's avatar
    ptrace: ensure JOBCTL_STOP_SIGMASK is not zero after detach · 8a88951b
    Oleg Nesterov authored
    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: default avatarTejun Heo <tj@kernel.org>
    Cc: <stable@kernel.org>		[3.1]
    Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    8a88951b
signal.c 82.9 KB