1 files changed, 77 insertions, 34 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 7c4b7ae714d4..9b04631acde8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -626,7 +626,8 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
  *
  * All callers have to hold the siglock.
  */
-int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info)
+int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
+		   kernel_siginfo_t *info, enum pid_type *type)
 {
 	bool resched_timer = false;
 	int signr;
@@ -634,8 +635,10 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *in
 	/* We only dequeue private signals from ourselves, we don't let
 	 * signalfd steal them
 	 */
+	*type = PIDTYPE_PID;
 	signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer);
 	if (!signr) {
+		*type = PIDTYPE_TGID;
 		signr = __dequeue_signal(&tsk->signal->shared_pending,
 					 mask, info, &resched_timer);
 #ifdef CONFIG_POSIX_TIMERS
@@ -903,8 +906,8 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force)
 	struct task_struct *t;
 	sigset_t flush;
 
-	if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) {
-		if (!(signal->flags & SIGNAL_GROUP_EXIT))
+	if (signal->flags & SIGNAL_GROUP_EXIT) {
+		if (signal->core_state)
 			return sig == SIGKILL;
 		/*
 		 * The process is in the middle of dying, nothing to do.
@@ -1029,7 +1032,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
 	 * then start taking the whole group down immediately.
 	 */
 	if (sig_fatal(p, sig) &&
-	    !(signal->flags & SIGNAL_GROUP_EXIT) &&
+	    (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
 	    !sigismember(&t->real_blocked, sig) &&
 	    (sig == SIGKILL || !p->ptrace)) {
 		/*
@@ -1298,6 +1301,12 @@ int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p
 	return ret;
 }
 
+enum sig_handler {
+	HANDLER_CURRENT, /* If reachable use the current handler */
+	HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */
+	HANDLER_EXIT,	 /* Only visible as the process exit code */
+};
+
 /*
  * Force a signal that the process can't ignore: if necessary
  * we unblock the signal and change any SIG_IGN to SIG_DFL.
@@ -1310,7 +1319,8 @@ int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p
  * that is why we also clear SIGNAL_UNKILLABLE.
  */
 static int
-force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool sigdfl)
+force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
+	enum sig_handler handler)
 {
 	unsigned long int flags;
 	int ret, blocked, ignored;
@@ -1321,9 +1331,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool
 	action = &t->sighand->action[sig-1];
 	ignored = action->sa.sa_handler == SIG_IGN;
 	blocked = sigismember(&t->blocked, sig);
-	if (blocked || ignored || sigdfl) {
+	if (blocked || ignored || (handler != HANDLER_CURRENT)) {
 		action->sa.sa_handler = SIG_DFL;
-		action->sa.sa_flags |= SA_IMMUTABLE;
+		if (handler == HANDLER_EXIT)
+			action->sa.sa_flags |= SA_IMMUTABLE;
 		if (blocked) {
 			sigdelset(&t->blocked, sig);
 			recalc_sigpending_and_wake(t);
@@ -1331,9 +1342,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool
 	}
 	/*
 	 * 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);
@@ -1343,7 +1355,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool
 
 int force_sig_info(struct kernel_siginfo *info)
 {
-	return force_sig_info_to_task(info, current, false);
+	return force_sig_info_to_task(info, current, HANDLER_CURRENT);
 }
 
 /*
@@ -1660,7 +1672,20 @@ void force_fatal_sig(int sig)
 	info.si_code = SI_KERNEL;
 	info.si_pid = 0;
 	info.si_uid = 0;
-	force_sig_info_to_task(&info, current, true);
+	force_sig_info_to_task(&info, current, HANDLER_SIG_DFL);
+}
+
+void force_exit_sig(int sig)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code = SI_KERNEL;
+	info.si_pid = 0;
+	info.si_uid = 0;
+	force_sig_info_to_task(&info, current, HANDLER_EXIT);
 }
 
 /*
@@ -1693,7 +1718,7 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_flags = flags;
 	info.si_isr = isr;
 #endif
-	return force_sig_info_to_task(&info, t, false);
+	return force_sig_info_to_task(&info, t, HANDLER_CURRENT);
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
@@ -1799,6 +1824,7 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
  * force_sig_seccomp - signals the task to allow in-process syscall emulation
  * @syscall: syscall number to send to userland
  * @reason: filter-supplied reason code to send to userland (via si_errno)
+ * @force_coredump: true to trigger a coredump
  *
  * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
  */
@@ -1813,7 +1839,8 @@ int force_sig_seccomp(int syscall, int reason, bool force_coredump)
 	info.si_errno = reason;
 	info.si_arch = syscall_get_arch(current);
 	info.si_syscall = syscall;
-	return force_sig_info_to_task(&info, current, force_coredump);
+	return force_sig_info_to_task(&info, current,
+		force_coredump ? HANDLER_EXIT : HANDLER_CURRENT);
 }
 
 /* For the crazy architectures that include trap information in
@@ -2361,7 +2388,8 @@ static bool do_signal_stop(int signr)
 		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
 
 		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
-		    unlikely(signal_group_exit(sig)))
+		    unlikely(sig->flags & SIGNAL_GROUP_EXIT) ||
+		    unlikely(sig->group_exec_task))
 			return false;
 		/*
 		 * There is no group stop already in progress.  We must
@@ -2522,7 +2550,7 @@ static void do_freezer_trap(void)
 	freezable_schedule();
 }
 
-static int ptrace_signal(int signr, kernel_siginfo_t *info)
+static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
 {
 	/*
 	 * We do not check sig_kernel_stop(signr) but set this marker
@@ -2562,8 +2590,9 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info)
 	}
 
 	/* If the (new) signal is now blocked, requeue it.  */
-	if (sigismember(&current->blocked, signr)) {
-		send_signal(signr, info, current, PIDTYPE_PID);
+	if (sigismember(&current->blocked, signr) ||
+	    fatal_signal_pending(current)) {
+		send_signal(signr, info, current, type);
 		signr = 0;
 	}
 
@@ -2662,18 +2691,20 @@ relock:
 		goto relock;
 	}
 
-	/* Has this task already been marked for death? */
-	if (signal_group_exit(signal)) {
-		ksig->info.si_signo = signr = SIGKILL;
-		sigdelset(&current->pending.signal, SIGKILL);
-		trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
-				&sighand->action[SIGKILL - 1]);
-		recalc_sigpending();
-		goto fatal;
-	}
-
 	for (;;) {
 		struct k_sigaction *ka;
+		enum pid_type type;
+
+		/* Has this task already been marked for death? */
+		if ((signal->flags & SIGNAL_GROUP_EXIT) ||
+		     signal->group_exec_task) {
+			ksig->info.si_signo = signr = SIGKILL;
+			sigdelset(&current->pending.signal, SIGKILL);
+			trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
+				&sighand->action[SIGKILL - 1]);
+			recalc_sigpending();
+			goto fatal;
+		}
 
 		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
 		    do_signal_stop(0))
@@ -2706,16 +2737,18 @@ relock:
 		 * so that the instruction pointer in the signal stack
 		 * frame points to the faulting instruction.
 		 */
+		type = PIDTYPE_PID;
 		signr = dequeue_synchronous_signal(&ksig->info);
 		if (!signr)
-			signr = dequeue_signal(current, &current->blocked, &ksig->info);
+			signr = dequeue_signal(current, &current->blocked,
+					       &ksig->info, &type);
 
 		if (!signr)
 			break; /* will return 0 */
 
 		if (unlikely(current->ptrace) && (signr != SIGKILL) &&
 		    !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) {
-			signr = ptrace_signal(signr, &ksig->info);
+			signr = ptrace_signal(signr, &ksig->info, type);
 			if (!signr)
 				continue;
 		}
@@ -2841,13 +2874,13 @@ out:
 }
 
 /**
- * signal_delivered - 
+ * signal_delivered - called after signal delivery to update blocked signals
  * @ksig:		kernel signal struct
  * @stepping:		nonzero if debugger single-step or block-step in use
  *
  * This function should be called when a signal has successfully been
  * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask
- * is always blocked, and the signal itself is blocked unless %SA_NODEFER
+ * is always blocked), and the signal itself is blocked unless %SA_NODEFER
  * is set in @ksig->ka.sa.sa_flags.  Tracing is notified.
  */
 static void signal_delivered(struct ksignal *ksig, int stepping)
@@ -2920,7 +2953,7 @@ void exit_signals(struct task_struct *tsk)
 	 */
 	cgroup_threadgroup_change_begin(tsk);
 
-	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
+	if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
 		tsk->flags |= PF_EXITING;
 		cgroup_threadgroup_change_end(tsk);
 		return;
@@ -3540,6 +3573,7 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
 	ktime_t *to = NULL, timeout = KTIME_MAX;
 	struct task_struct *tsk = current;
 	sigset_t mask = *which;
+	enum pid_type type;
 	int sig, ret = 0;
 
 	if (ts) {
@@ -3556,7 +3590,7 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
 	signotset(&mask);
 
 	spin_lock_irq(&tsk->sighand->siglock);
-	sig = dequeue_signal(tsk, &mask, info);
+	sig = dequeue_signal(tsk, &mask, info, &type);
 	if (!sig && timeout) {
 		/*
 		 * None ready, temporarily unblock those we're interested
@@ -3575,7 +3609,7 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
 		spin_lock_irq(&tsk->sighand->siglock);
 		__set_task_blocked(tsk, &tsk->real_blocked);
 		sigemptyset(&tsk->real_blocked);
-		sig = dequeue_signal(tsk, &mask, info);
+		sig = dequeue_signal(tsk, &mask, info, &type);
 	}
 	spin_unlock_irq(&tsk->sighand->siglock);
 
@@ -4163,6 +4197,15 @@ do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
 				ss_mode != 0))
 			return -EINVAL;
 
+		/*
+		 * Return before taking any locks if no actual
+		 * sigaltstack changes were requested.
+		 */
+		if (t->sas_ss_sp == (unsigned long)ss_sp &&
+		    t->sas_ss_size == ss_size &&
+		    t->sas_ss_flags == ss_flags)
+			return 0;
+
 		sigaltstack_lock();
 		if (ss_mode == SS_DISABLE) {
 			ss_size = 0;