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64c134f90f
We need to make sure that there's no possible faulting instruction between a VarDef and that variable being fully initialized. If there was, then anything scanning the stack during the handling of that fault will see a live but uninitialized variable on the stack. If we have: NilCheck p VarDef x x = *p We can't rewrite that to VarDef x NilCheck p x = *p Particularly, even though *p faults on p==nil, we still have to do the explicit nil check before the VarDef. Fixes #32288 Change-Id: Ib8b88e6a5af3bf6f238ff5491ac86f53f3cf9fc9 Reviewed-on: https://go-review.googlesource.com/c/go/+/179239 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
49 lines
809 B
Go
49 lines
809 B
Go
// run
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// Copyright 2019 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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type T struct {
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s [1]string
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pad [16]uintptr
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}
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//go:noinline
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func f(t *int, p *int) []T {
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var res []T
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for {
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var e *T
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res = append(res, *e)
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}
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}
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func main() {
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defer func() {
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useStack(100) // force a stack copy
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// We're expecting a panic.
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// The bug in this issue causes a throw, which this recover() will not squash.
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recover()
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}()
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junk() // fill the stack with invalid pointers
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f(nil, nil)
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}
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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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//go:noinline
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func junk() uintptr {
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var a [128]uintptr // 1k of bad pointers on the stack
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for i := range a {
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a[i] = 0xaa
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}
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return a[12]
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}
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