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70 lines
1.2 KiB
70 lines
1.2 KiB
// run
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import "fmt"
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const N = 40
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func main() {
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var x [N]int // stack-allocated memory
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for i := range x {
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x[i] = 0x999
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}
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// This defer checks to see if x is uncorrupted.
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defer func(p *[N]int) {
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recover()
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for i := range p {
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if p[i] != 0x999 {
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for j := range p {
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fmt.Printf("p[%d]=0x%x\n", j, p[j])
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}
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panic("corrupted stack variable")
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}
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}
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}(&x)
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// This defer starts a new goroutine, which will (hopefully)
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// overwrite x on the garbage stack.
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defer func() {
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c := make(chan bool)
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go func() {
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useStack(1000)
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c <- true
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}()
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<-c
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}()
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// This defer causes a stack copy.
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// The old stack is now garbage.
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defer func() {
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useStack(1000)
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}()
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// Trigger a segfault.
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*g = 0
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// Make the return statement unreachable.
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// That makes the stack map at the deferreturn call empty.
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// In particular, the argument to the first defer is not
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// marked as a pointer, so it doesn't get adjusted
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// during the stack copy.
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for {
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}
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}
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var g *int64
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func useStack(n int) {
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if n == 0 {
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return
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}
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useStack(n - 1)
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}
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