mirror of
https://github.com/golang/go
synced 2024-11-23 19:20:03 -07:00
111d590f86
SSA compiler on AMD64 may spill Duff-adjusted address as scalar. If the object is on stack and the stack moves, the spilled address become invalid. Making the spill pointer-typed does not work. The Duff-adjusted address points to the memory before the area to be zeroed and may be invalid. This may cause stack scanning code panic. Fix it by doing Duff-adjustment in genValue, so the intermediate value is not seen by the reg allocator, and will not be spilled. Add a test to cover both cases. As it depends on allocation, it may be not always triggered. Fixes #16515. Change-Id: Ia81d60204782de7405b7046165ad063384ede0db Reviewed-on: https://go-review.googlesource.com/25309 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
54 lines
1.1 KiB
Go
54 lines
1.1 KiB
Go
// run
|
|
|
|
// Copyright 2016 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.
|
|
|
|
// issue 16515: spilled Duff-adjusted address may be invalid
|
|
|
|
package main
|
|
|
|
import "runtime"
|
|
|
|
type T [62]int // DUFFZERO with non-zero adjustment on AMD64
|
|
|
|
var sink interface{}
|
|
|
|
//go:noinline
|
|
func zero(x *T) {
|
|
// Two DUFFZEROs on the same address with a function call in between.
|
|
// Duff-adjusted address will be spilled and loaded
|
|
|
|
*x = T{} // DUFFZERO
|
|
runtime.GC()
|
|
(*x)[0] = 1
|
|
g() // call a function with large frame, trigger a stack move
|
|
*x = T{} // DUFFZERO again
|
|
}
|
|
|
|
//go:noinline
|
|
// a function with large frame
|
|
func g() {
|
|
var x [1000]int
|
|
_ = x
|
|
}
|
|
|
|
func main() {
|
|
var s struct { a T; b [8192-62]int } // allocate 64K, hopefully it's in a new span and a few bytes before it is garbage
|
|
sink = &s // force heap allocation
|
|
s.a[0] = 2
|
|
zero(&s.a)
|
|
if s.a[0] != 0 {
|
|
println("s.a[0] =", s.a[0])
|
|
panic("zeroing failed")
|
|
}
|
|
|
|
var a T // on stack
|
|
a[0] = 2
|
|
zero(&a)
|
|
if a[0] != 0 {
|
|
println("a[0] =", a[0])
|
|
panic("zeroing failed")
|
|
}
|
|
}
|