blob: d6224df017dc4b170ed775d6e8f3deb21dd84435 [file] [log] [blame]
// run
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
var nilp *int
var forceHeap interface{}
func main() {
// x is a pointer on the stack to heap-allocated memory.
x := new([32]*int)
forceHeap = x
forceHeap = nil
// Push a defer to be run when we panic below.
defer func() {
// Ignore the panic.
// Force a stack walk. Go 1.11 will fail because x is now
// considered live again.
// Make x live at the defer's PC.
// x is no longer live. Garbage collect the [32]*int on the
// heap.
// At this point x's dead stack slot points to dead memory.
// Trigger a sigpanic. Since this is an implicit panic, we
// don't have an explicit liveness map here.
// Traceback used to use the liveness map of the most recent defer,
// but in that liveness map, x will be live again even though
// it points to dead memory. The fix is to use the liveness
// map of a deferreturn call instead.
*nilp = 0