Messages in this thread Patch in this message | | | From | Jamie Iles <> | Subject | [PATCH] signal: don't remove SIGNAL_UNKILLABLE for traced tasks. | Date | Thu, 4 May 2017 13:51:36 +0100 |
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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.
Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Jamie Iles <jamie.iles@oracle.com> --- kernel/signal.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/signal.c b/kernel/signal.c index 7e59ebc2c25e..5516a0cda668 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1185,7 +1185,11 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) 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); -- 2.12.0.rc0
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