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-rw-r--r--kernel/signal.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 811b5d440617..3c8ea7a328e0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2780,6 +2780,39 @@ int set_compat_user_sigmask(const compat_sigset_t __user *usigmask,
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)
+{
+
+ 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 (signal_pending(current)) {
+ 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