From: Jamie Iles <jamie.iles@xxxxxxxxxx> Subject: signal: don't remove SIGNAL_UNKILLABLE for traced tasks. When forcing a signal, SIGNAL_UNKILLABLE is removed to prevent recursive faults, but this is undesirable when tracing. For example, debugging an init process (whether global or namespace), hitting a breakpoint and SIGTRAP will force SIGTRAP and then remove SIGNAL_UNKILLABLE. Everything continues fine, but then once debugging has finished, the init process is left killable which is unlikely what the user expects, resulting in either an accidentally killed init or an init that stops reaping zombies. Link: http://lkml.kernel.org/r/20170815112806.10728-1-jamie.iles@xxxxxxxxxx Signed-off-by: Jamie Iles <jamie.iles@xxxxxxxxxx> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/signal.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff -puN kernel/signal.c~signal-dont-remove-signal_unkillable-for-traced-tasks kernel/signal.c --- a/kernel/signal.c~signal-dont-remove-signal_unkillable-for-traced-tasks +++ a/kernel/signal.c @@ -1194,7 +1194,11 @@ force_sig_info(int sig, struct siginfo * recalc_sigpending_and_wake(t); } } - if (action->sa.sa_handler == SIG_DFL) + /* + * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect + * debugging to leave init killable. + */ + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
