mirror of
https://github.com/golang/go
synced 2024-11-05 17:46:16 -07:00
46 lines
1.1 KiB
Go
46 lines
1.1 KiB
Go
|
// 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 (
|
||
|
|
"runtime"
|
||
|
|
)
|
||
|
|
|
||
|
|
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.
|
||
|
|
recover()
|
||
|
|
// Force a stack walk. Go 1.11 will fail because x is now
|
||
|
|
// considered live again.
|
||
|
|
runtime.GC()
|
||
|
|
}()
|
||
|
|
// Make x live at the defer's PC.
|
||
|
|
runtime.KeepAlive(x)
|
||
|
|
|
||
|
|
// x is no longer live. Garbage collect the [32]*int on the
|
||
|
|
// heap.
|
||
|
|
runtime.GC()
|
||
|
|
// 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
|
||
|
|
}
|