Commit 5c72263e authored by Kees Cook's avatar Kees Cook
Browse files

signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE 



Fatal SIGSYS signals (i.e. seccomp RET_KILL_* syscall filter actions)
were not being delivered to ptraced pid namespace init processes. Make
sure the SIGNAL_UNKILLABLE doesn't get set for these cases.

Reported-by: default avatarRobert Święcki <robert@swiecki.net>
Suggested-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Fixes: 00b06da2 ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/lkml/878rui8u4a.fsf@email.froward.int.ebiederm.org
parent 26291c54

kernel/signal.c

+3 −2
Original line number Diff line number Diff line
@@ -1342,9 +1342,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, 
	}

	/*

	 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect

	 * debugging to leave init killable.

	 * debugging to leave init killable. But HANDLER_EXIT is always fatal.

	 */

	if (action->sa.sa_handler == SIG_DFL && !t->ptrace)

	if (action->sa.sa_handler == SIG_DFL &&

	    (!t->ptrace || (handler == HANDLER_EXIT)))

		t->signal->flags &= ~SIGNAL_UNKILLABLE;

	ret = send_signal(sig, info, t, PIDTYPE_PID);

	spin_unlock_irqrestore(&t->sighand->siglock, flags);