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b39e0f461c
Ironically, checkptrAlignment had a latent case of bad pointer arithmetic: if ptr is nil, then `add(ptr, size-1)` might produce an illegal pointer value. The fix is to simply check for nil at the top of checkptrAlignment, and short-circuit if so. This CL also adds a more explicit bounds check in checkptrStraddles, rather than relying on `add(ptr, size-1)` to wrap around. I don't think this is necessary today, but it seems prudent to be careful. Fixes #47430. Change-Id: I5c50b2f7f41415dbebbd803e1b8e7766ca95e1fd Reviewed-on: https://go-review.googlesource.com/c/go/+/338029 Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
98 lines
1.9 KiB
Go
98 lines
1.9 KiB
Go
// 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 (
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"runtime"
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"time"
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"unsafe"
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)
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func init() {
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register("CheckPtrAlignmentNoPtr", CheckPtrAlignmentNoPtr)
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register("CheckPtrAlignmentPtr", CheckPtrAlignmentPtr)
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register("CheckPtrAlignmentNilPtr", CheckPtrAlignmentNilPtr)
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register("CheckPtrArithmetic", CheckPtrArithmetic)
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register("CheckPtrArithmetic2", CheckPtrArithmetic2)
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register("CheckPtrSize", CheckPtrSize)
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register("CheckPtrSmall", CheckPtrSmall)
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register("CheckPtrSliceOK", CheckPtrSliceOK)
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register("CheckPtrSliceFail", CheckPtrSliceFail)
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}
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func CheckPtrAlignmentNoPtr() {
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var x [2]int64
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p := unsafe.Pointer(&x[0])
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sink2 = (*int64)(unsafe.Pointer(uintptr(p) + 1))
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}
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func CheckPtrAlignmentPtr() {
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var x [2]int64
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p := unsafe.Pointer(&x[0])
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sink2 = (**int64)(unsafe.Pointer(uintptr(p) + 1))
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}
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// CheckPtrAlignmentNilPtr tests that checkptrAlignment doesn't crash
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// on nil pointers (#47430).
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func CheckPtrAlignmentNilPtr() {
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var do func(int)
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do = func(n int) {
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// Inflate the stack so runtime.shrinkstack gets called during GC
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if n > 0 {
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do(n - 1)
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}
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var p unsafe.Pointer
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_ = (*int)(p)
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}
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go func() {
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for {
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runtime.GC()
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}
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}()
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go func() {
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for i := 0; ; i++ {
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do(i % 1024)
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}
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}()
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time.Sleep(time.Second)
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}
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func CheckPtrArithmetic() {
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var x int
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i := uintptr(unsafe.Pointer(&x))
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sink2 = (*int)(unsafe.Pointer(i))
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}
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func CheckPtrArithmetic2() {
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var x [2]int64
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p := unsafe.Pointer(&x[1])
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var one uintptr = 1
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sink2 = unsafe.Pointer(uintptr(p) & ^one)
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}
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func CheckPtrSize() {
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p := new(int64)
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sink2 = p
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sink2 = (*[100]int64)(unsafe.Pointer(p))
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}
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func CheckPtrSmall() {
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sink2 = unsafe.Pointer(uintptr(1))
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}
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func CheckPtrSliceOK() {
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p := new([4]int64)
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sink2 = unsafe.Slice(&p[1], 3)
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}
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func CheckPtrSliceFail() {
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p := new(int64)
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sink2 = p
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sink2 = unsafe.Slice(p, 100)
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}
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