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cmd/compile, runtime: store pointers to go:notinheap types indirectly

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pointers to go:notinheap types should be treated as scalars. That
means they shouldn't be stored directly in interfaces, or directly
in reflect.Value.ptr.

Also be sure to use uintpr to compare such pointers in reflect.DeepEqual.

Fixes #42076

Change-Id: I53735f6d434e9c3108d4940bd1bae14c61ef2a74
Reviewed-on: https://go-review.googlesource.com/c/go/+/264480
Trust: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Keith Randall 2020-10-22 16:37:19 -07:00
parent 933721b8c7
commit 009d714098
6 changed files with 81 additions and 19 deletions
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12
src/reflect/value.go
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@ -90,6 +90,7 @@ func (f flag) ro() flag {
// pointer returns the underlying pointer represented by v.
// v.Kind() must be Ptr, Map, Chan, Func, or UnsafePointer
// if v.Kind() == Ptr, the base type must not be go:notinheap.
func (v Value) pointer() unsafe.Pointer {
if v.typ.size != ptrSize || !v.typ.pointers() {
panic("can't call pointer on a non-pointer Value")
@ -1453,7 +1454,16 @@ func (v Value) Pointer() uintptr {
// TODO: deprecate
k := v.kind()
switch k {
case Chan, Map, Ptr, UnsafePointer:
case Ptr:
if v.typ.ptrdata == 0 {
// Handle pointers to go:notinheap types directly,
// so we never materialize such pointers as an
// unsafe.Pointer. (Such pointers are always indirect.)
// See issue 42076.
return *(*uintptr)(v.ptr)
}
fallthrough
case Chan, Map, UnsafePointer:
return uintptr(v.pointer())
case Func:
if v.flag&flagMethod != 0 {