1 files changed, 101 insertions, 39 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 0af8868525d..3d09cf6cde7 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -31,6 +31,7 @@
 #include <linux/nsproxy.h>
 #include <linux/user_namespace.h>
 #include <linux/uprobes.h>
+#include <linux/compat.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/signal.h>
 
@@ -679,23 +680,17 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
  * No need to set need_resched since signal event passing
  * goes through ->blocked
  */
-void signal_wake_up(struct task_struct *t, int resume)
+void signal_wake_up_state(struct task_struct *t, unsigned int state)
 {
-	unsigned int mask;
-
 	set_tsk_thread_flag(t, TIF_SIGPENDING);
-
 	/*
-	 * For SIGKILL, we want to wake it up in the stopped/traced/killable
+	 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable
 	 * case. We don't check t->state here because there is a race with it
 	 * executing another processor and just now entering stopped state.
 	 * By using wake_up_state, we ensure the process will wake up and
 	 * handle its death signal.
 	 */
-	mask = TASK_INTERRUPTIBLE;
-	if (resume)
-		mask |= TASK_WAKEKILL;
-	if (!wake_up_state(t, mask))
+	if (!wake_up_state(t, state | TASK_INTERRUPTIBLE))
 		kick_process(t);
 }
 
@@ -843,7 +838,7 @@ static void ptrace_trap_notify(struct task_struct *t)
 	assert_spin_locked(&t->sighand->siglock);
 
 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
-	signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
+	ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 }
 
 /*
@@ -1159,8 +1154,9 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	return __send_signal(sig, info, t, group, from_ancestor_ns);
 }
 
-static void print_fatal_signal(struct pt_regs *regs, int signr)
+static void print_fatal_signal(int signr)
 {
+	struct pt_regs *regs = signal_pt_regs();
 	printk("%s/%d: potentially unexpected fatal signal %d.\n",
 		current->comm, task_pid_nr(current), signr);
 
@@ -1752,7 +1748,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
 	 * see comment in do_notify_parent() about the following 4 lines
 	 */
 	rcu_read_lock();
-	info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
+	info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent));
 	info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
 	rcu_read_unlock();
 
@@ -1798,6 +1794,10 @@ static inline int may_ptrace_stop(void)
 	 * If SIGKILL was already sent before the caller unlocked
 	 * ->siglock we must see ->core_state != NULL. Otherwise it
 	 * is safe to enter schedule().
+	 *
+	 * This is almost outdated, a task with the pending SIGKILL can't
+	 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported
+	 * after SIGKILL was already dequeued.
 	 */
 	if (unlikely(current->mm->core_state) &&
 	    unlikely(current->mm == current->parent->mm))
@@ -1908,7 +1908,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 		preempt_disable();
 		read_unlock(&tasklist_lock);
 		preempt_enable_no_resched();
-		schedule();
+		freezable_schedule();
 	} else {
 		/*
 		 * By the time we got the lock, our tracer went away.
@@ -1923,6 +1923,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 		if (gstop_done)
 			do_notify_parent_cldstop(current, false, why);
 
+		/* tasklist protects us from ptrace_freeze_traced() */
 		__set_current_state(TASK_RUNNING);
 		if (clear_code)
 			current->exit_code = 0;
@@ -1930,13 +1931,6 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 	}
 
 	/*
-	 * While in TASK_TRACED, we were considered "frozen enough".
-	 * Now that we woke up, it's crucial if we're supposed to be
-	 * frozen that we freeze now before running anything substantial.
-	 */
-	try_to_freeze();
-
-	/*
 	 * We are back.  Now reacquire the siglock before touching
 	 * last_siginfo, so that we are sure to have synchronized with
 	 * any signal-sending on another CPU that wants to examine it.
@@ -2092,7 +2086,7 @@ static bool do_signal_stop(int signr)
 		}
 
 		/* Now we don't run again until woken by SIGCONT or SIGKILL */
-		schedule();
+		freezable_schedule();
 		return true;
 	} else {
 		/*
@@ -2138,10 +2132,9 @@ static void do_jobctl_trap(void)
 	}
 }
 
-static int ptrace_signal(int signr, siginfo_t *info,
-			 struct pt_regs *regs, void *cookie)
+static int ptrace_signal(int signr, siginfo_t *info)
 {
-	ptrace_signal_deliver(regs, cookie);
+	ptrace_signal_deliver();
 	/*
 	 * We do not check sig_kernel_stop(signr) but set this marker
 	 * unconditionally because we do not know whether debugger will
@@ -2200,15 +2193,14 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 	if (unlikely(uprobe_deny_signal()))
 		return 0;
 
-relock:
 	/*
-	 * We'll jump back here after any time we were stopped in TASK_STOPPED.
-	 * While in TASK_STOPPED, we were considered "frozen enough".
-	 * Now that we woke up, it's crucial if we're supposed to be
-	 * frozen that we freeze now before running anything substantial.
+	 * Do this once, we can't return to user-mode if freezing() == T.
+	 * do_signal_stop() and ptrace_stop() do freezable_schedule() and
+	 * thus do not need another check after return.
 	 */
 	try_to_freeze();
 
+relock:
 	spin_lock_irq(&sighand->siglock);
 	/*
 	 * Every stopped thread goes here after wakeup. Check to see if
@@ -2265,8 +2257,7 @@ relock:
 			break; /* will return 0 */
 
 		if (unlikely(current->ptrace) && signr != SIGKILL) {
-			signr = ptrace_signal(signr, info,
-					      regs, cookie);
+			signr = ptrace_signal(signr, info);
 			if (!signr)
 				continue;
 		}
@@ -2351,7 +2342,7 @@ relock:
 
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
-				print_fatal_signal(regs, info->si_signo);
+				print_fatal_signal(info->si_signo);
 			/*
 			 * If it was able to dump core, this kills all
 			 * other threads in the group and synchronizes with
@@ -2360,7 +2351,7 @@ relock:
 			 * first and our do_group_exit call below will use
 			 * that value and ignore the one we pass it.
 			 */
-			do_coredump(info, regs);
+			do_coredump(info);
 		}
 
 		/*
@@ -2536,11 +2527,8 @@ static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
  */
 void set_current_blocked(sigset_t *newset)
 {
-	struct task_struct *tsk = current;
 	sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
-	spin_lock_irq(&tsk->sighand->siglock);
-	__set_task_blocked(tsk, newset);
-	spin_unlock_irq(&tsk->sighand->siglock);
+	__set_current_blocked(newset);
 }
 
 void __set_current_blocked(const sigset_t *newset)
@@ -3103,6 +3091,80 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
 out:
 	return error;
 }
+#ifdef CONFIG_GENERIC_SIGALTSTACK
+SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
+{
+	return do_sigaltstack(uss, uoss, current_user_stack_pointer());
+}
+#endif
+
+int restore_altstack(const stack_t __user *uss)
+{
+	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
+	/* squash all but EFAULT for now */
+	return err == -EFAULT ? err : 0;
+}
+
+int __save_altstack(stack_t __user *uss, unsigned long sp)
+{
+	struct task_struct *t = current;
+	return  __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
+		__put_user(sas_ss_flags(sp), &uss->ss_flags) |
+		__put_user(t->sas_ss_size, &uss->ss_size);
+}
+
+#ifdef CONFIG_COMPAT
+#ifdef CONFIG_GENERIC_SIGALTSTACK
+COMPAT_SYSCALL_DEFINE2(sigaltstack,
+			const compat_stack_t __user *, uss_ptr,
+			compat_stack_t __user *, uoss_ptr)
+{
+	stack_t uss, uoss;
+	int ret;
+	mm_segment_t seg;
+
+	if (uss_ptr) {
+		compat_stack_t uss32;
+
+		memset(&uss, 0, sizeof(stack_t));
+		if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
+			return -EFAULT;
+		uss.ss_sp = compat_ptr(uss32.ss_sp);
+		uss.ss_flags = uss32.ss_flags;
+		uss.ss_size = uss32.ss_size;
+	}
+	seg = get_fs();
+	set_fs(KERNEL_DS);
+	ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
+			     (stack_t __force __user *) &uoss,
+			     compat_user_stack_pointer());
+	set_fs(seg);
+	if (ret >= 0 && uoss_ptr)  {
+		if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
+		    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
+		    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
+		    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
+			ret = -EFAULT;
+	}
+	return ret;
+}
+
+int compat_restore_altstack(const compat_stack_t __user *uss)
+{
+	int err = compat_sys_sigaltstack(uss, NULL);
+	/* squash all but -EFAULT for now */
+	return err == -EFAULT ? err : 0;
+}
+
+int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
+{
+	struct task_struct *t = current;
+	return  __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) |
+		__put_user(sas_ss_flags(sp), &uss->ss_flags) |
+		__put_user(t->sas_ss_size, &uss->ss_size);
+}
+#endif
+#endif
 
 #ifdef __ARCH_WANT_SYS_SIGPENDING
 
@@ -3139,7 +3201,6 @@ SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
 	if (nset) {
 		if (copy_from_user(&new_set, nset, sizeof(*nset)))
 			return -EFAULT;
-		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
 
 		new_blocked = current->blocked;
 
@@ -3157,7 +3218,7 @@ SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
 			return -EINVAL;
 		}
 
-		__set_current_blocked(&new_blocked);
+		set_current_blocked(&new_blocked);
 	}
 
 	if (oset) {
@@ -3221,6 +3282,7 @@ SYSCALL_DEFINE1(ssetmask, int, newmask)
 	int old = current->blocked.sig[0];
 	sigset_t newset;
 
+	siginitset(&newset, newmask);
 	set_current_blocked(&newset);
 
 	return old;