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cmd/compile: don't ICE on unaligned offsets for pointer writes

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User code is unlikely to be correct, but don't crash the compiler
when the offset of a pointer in an object is not a multiple of the
pointer size.

Fixes #61187

Change-Id: Ie56bfcb38556c5dd6f702ae4ec1d4534c6acd420
Reviewed-on: https://go-review.googlesource.com/c/go/+/508555
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
This commit is contained in:
Keith Randall 2023-07-08 08:46:37 -07:00
parent 5c15498609
commit c4db811e44
2 changed files with 27 additions and 2 deletions
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7
src/cmd/compile/internal/ssa/writebarrier.go
View File

@ -53,7 +53,10 @@ func mightContainHeapPointer(ptr *Value, size int64, mem *Value, zeroes map[ID]Z
} }
ptrSize := ptr.Block.Func.Config.PtrSize ptrSize := ptr.Block.Func.Config.PtrSize
if off%ptrSize != 0 || size%ptrSize != 0 { if off%ptrSize != 0 {
return true // see issue 61187
}
if size%ptrSize != 0 {
ptr.Fatalf("unaligned pointer write") ptr.Fatalf("unaligned pointer write")
} }
if off < 0 || off+size > 64*ptrSize { if off < 0 || off+size > 64*ptrSize {
@ -130,7 +133,7 @@ func needWBdst(ptr, mem *Value, zeroes map[ID]ZeroRegion) bool {
} }
ptrSize := ptr.Block.Func.Config.PtrSize ptrSize := ptr.Block.Func.Config.PtrSize
if off%ptrSize != 0 { if off%ptrSize != 0 {
ptr.Fatalf("unaligned pointer write") return true // see issue 61187
} }
if off < 0 || off >= 64*ptrSize { if off < 0 || off >= 64*ptrSize {
// write goes off end of tracked offsets // write goes off end of tracked offsets

22
test/fixedbugs/issue61187.go Normal file
View File

@ -0,0 +1,22 @@
// compile
// Copyright 2023 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 (
"fmt"
"reflect"
"unsafe"
)
var slice = []byte{'H', 'e', 'l', 'l', 'o', ','}
func main() {
ptr := uintptr(unsafe.Pointer(&slice)) + 100
header := (*reflect.SliceHeader)(unsafe.Pointer(ptr))
header.Data += 1
fmt.Printf("%d %d\n", cap(slice), header.Cap)
}