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cmd/compile: recognize reflect.{Slice,String}Header for -d=checkptr

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Avoids false positive pointer arithmetic panic.

Fixes #35027.

Change-Id: Idd008caaab25fcf739327ac50a021b835ef13def
Reviewed-on: https://go-review.googlesource.com/c/go/+/202560
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Matthew Dempsky 2019-10-21 12:44:42 -07:00
parent 3409ce39bf
commit b282efa022
2 changed files with 27 additions and 0 deletions
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4
src/cmd/compile/internal/gc/walk.go
View File

@ -3941,6 +3941,10 @@ func walkCheckPtrArithmetic(n *Node, init *Nodes) *Node {
return n
}
if n.Left.Op == ODOTPTR && isReflectHeaderDataField(n.Left) {
return n
}
// Find original unsafe.Pointer operands involved in this
// arithmetic expression.
//

23
test/fixedbugs/issue35027.go Normal file
View File

@ -0,0 +1,23 @@
// run -gcflags=-d=checkptr
// Copyright 2019 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 (
"reflect"
"unsafe"
)
var s []int
func main() {
s = []int{42}
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
x := *(*int)(unsafe.Pointer(h.Data))
if x != 42 {
panic(x)
}
}