1 files changed, 42 insertions, 64 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 07da8def4329..00448edd0282 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -408,27 +408,32 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
 {
 	struct sigqueue *q = NULL;
 	struct user_struct *user;
+	int sigpending;
 
 	/*
 	 * Protect access to @t credentials. This can go away when all
 	 * callers hold rcu read lock.
+	 *
+	 * NOTE! A pending signal will hold on to the user refcount,
+	 * and we get/put the refcount only when the sigpending count
+	 * changes from/to zero.
 	 */
 	rcu_read_lock();
-	user = get_uid(__task_cred(t)->user);
-	atomic_inc(&user->sigpending);
+	user = __task_cred(t)->user;
+	sigpending = atomic_inc_return(&user->sigpending);
+	if (sigpending == 1)
+		get_uid(user);
 	rcu_read_unlock();
 
-	if (override_rlimit ||
-	    atomic_read(&user->sigpending) <=
-			task_rlimit(t, RLIMIT_SIGPENDING)) {
+	if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
 		q = kmem_cache_alloc(sigqueue_cachep, flags);
 	} else {
 		print_dropped_signal(sig);
 	}
 
 	if (unlikely(q == NULL)) {
-		atomic_dec(&user->sigpending);
-		free_uid(user);
+		if (atomic_dec_and_test(&user->sigpending))
+			free_uid(user);
 	} else {
 		INIT_LIST_HEAD(&q->list);
 		q->flags = 0;
@@ -442,8 +447,8 @@ static void __sigqueue_free(struct sigqueue *q)
 {
 	if (q->flags & SIGQUEUE_PREALLOC)
 		return;
-	atomic_dec(&q->user->sigpending);
-	free_uid(q->user);
+	if (atomic_dec_and_test(&q->user->sigpending))
+		free_uid(q->user);
 	kmem_cache_free(sigqueue_cachep, q);
 }
 
@@ -1486,15 +1491,15 @@ int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
 	unsigned long flags;
 	int ret = -EINVAL;
 
+	if (!valid_signal(sig))
+		return ret;
+
 	clear_siginfo(&info);
 	info.si_signo = sig;
 	info.si_errno = errno;
 	info.si_code = SI_ASYNCIO;
 	*((sigval_t *)&info.si_pid) = addr;
 
-	if (!valid_signal(sig))
-		return ret;
-
 	rcu_read_lock();
 	p = pid_task(pid, PIDTYPE_PID);
 	if (!p) {
@@ -1876,7 +1881,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 		 * This is only possible if parent == real_parent.
 		 * Check if it has changed security domain.
 		 */
-		if (tsk->parent_exec_id != tsk->parent->self_exec_id)
+		if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id))
 			sig = SIGCHLD;
 	}
 
@@ -1938,8 +1943,12 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
 			sig = 0;
 	}
+	/*
+	 * Send with __send_signal as si_pid and si_uid are in the
+	 * parent's namespaces.
+	 */
 	if (valid_signal(sig) && sig)
-		__group_send_sig_info(sig, &info, tsk->parent);
+		__send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);
 	__wake_up_parent(tsk, tsk->parent);
 	spin_unlock_irqrestore(&psig->siglock, flags);
 
@@ -2907,80 +2916,49 @@ EXPORT_SYMBOL(sigprocmask);
  *
  * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
  * epoll_pwait where a new sigmask is passed from userland for the syscalls.
+ *
+ * Note that it does set_restore_sigmask() in advance, so it must be always
+ * paired with restore_saved_sigmask_unless() before return from syscall.
  */
-int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set,
-		     sigset_t *oldset, size_t sigsetsize)
+int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
 {
-	if (!usigmask)
-		return 0;
+	sigset_t kmask;
 
+	if (!umask)
+		return 0;
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;
-	if (copy_from_user(set, usigmask, sizeof(sigset_t)))
+	if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
 		return -EFAULT;
 
-	*oldset = current->blocked;
-	set_current_blocked(set);
+	set_restore_sigmask();
+	current->saved_sigmask = current->blocked;
+	set_current_blocked(&kmask);
 
 	return 0;
 }
-EXPORT_SYMBOL(set_user_sigmask);
 
 #ifdef CONFIG_COMPAT
-int set_compat_user_sigmask(const compat_sigset_t __user *usigmask,
-			    sigset_t *set, sigset_t *oldset,
+int set_compat_user_sigmask(const compat_sigset_t __user *umask,
 			    size_t sigsetsize)
 {
-	if (!usigmask)
-		return 0;
+	sigset_t kmask;
 
+	if (!umask)
+		return 0;
 	if (sigsetsize != sizeof(compat_sigset_t))
 		return -EINVAL;
-	if (get_compat_sigset(set, usigmask))
+	if (get_compat_sigset(&kmask, umask))
 		return -EFAULT;
 
-	*oldset = current->blocked;
-	set_current_blocked(set);
+	set_restore_sigmask();
+	current->saved_sigmask = current->blocked;
+	set_current_blocked(&kmask);
 
 	return 0;
 }
-EXPORT_SYMBOL(set_compat_user_sigmask);
 #endif
 
-/*
- * restore_user_sigmask:
- * usigmask: sigmask passed in from userland.
- * sigsaved: saved sigmask when the syscall started and changed the sigmask to
- *           usigmask.
- *
- * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
- * epoll_pwait where a new sigmask is passed in from userland for the syscalls.
- */
-void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved,
-				bool interrupted)
-{
-
-	if (!usigmask)
-		return;
-	/*
-	 * When signals are pending, do not restore them here.
-	 * Restoring sigmask here can lead to delivering signals that the above
-	 * syscalls are intended to block because of the sigmask passed in.
-	 */
-	if (interrupted) {
-		current->saved_sigmask = *sigsaved;
-		set_restore_sigmask();
-		return;
-	}
-
-	/*
-	 * This is needed because the fast syscall return path does not restore
-	 * saved_sigmask when signals are not pending.
-	 */
-	set_current_blocked(sigsaved);
-}
-EXPORT_SYMBOL(restore_user_sigmask);
-
 /**
  *  sys_rt_sigprocmask - change the list of currently blocked signals
  *  @how: whether to add, remove, or set signals