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[release-branch.go1.24] cmd/compile: don't pull constant offsets out of pointer arithmetic

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This could lead to manufacturing a pointer that points outside
its original allocation.

Bug was introduced in CL 629858.

Fixes #71938

Change-Id: Ia86ab0b65ce5f80a8e0f4f4c81babd07c5904f8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/652078
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
(cherry picked from commit 8b8bff7bb29210db868306cd07a03fb15e247b2f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/652855
This commit is contained in:
Keith Randall 2025-02-24 13:07:29 -08:00 committed by Michael Pratt
parent 0bfde51e0d
commit 949eae84df
3 changed files with 120 additions and 52 deletions
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10
src/cmd/compile/internal/ssa/_gen/ARM64.rules
View File

@ -1148,10 +1148,12 @@
(SUB a l:(MNEGW x y)) && v.Type.Size() <= 4 && l.Uses==1 && clobber(l) => (MADDW a x y)
// madd/msub can't take constant arguments, so do a bit of reordering if a non-constant is available.
(ADD a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (ADDconst [c] (ADD <v.Type> a m))
(ADD a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (SUBconst [c] (ADD <v.Type> a m))
(SUB a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (SUBconst [c] (SUB <v.Type> a m))
(SUB a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 => (ADDconst [c] (SUB <v.Type> a m))
// Note: don't reorder arithmetic concerning pointers, as we must ensure that
// no intermediate computations are invalid pointers.
(ADD <t> a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (ADDconst [c] (ADD <v.Type> a m))
(ADD <t> a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (SUBconst [c] (ADD <v.Type> a m))
(SUB <t> a p:(ADDconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (SUBconst [c] (SUB <v.Type> a m))
(SUB <t> a p:(SUBconst [c] m:((MUL|MULW|MNEG|MNEGW) _ _))) && p.Uses==1 && m.Uses==1 && !t.IsPtrShaped() => (ADDconst [c] (SUB <v.Type> a m))
// optimize ADCSflags, SBCSflags and friends
(ADCSflags x y (Select1 <types.TypeFlags> (ADDSconstflags [-1] (ADCzerocarry <typ.UInt64> c)))) => (ADCSflags x y c)

112
src/cmd/compile/internal/ssa/rewriteARM64.go
View File

@ -1331,10 +1331,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1343,7 +1344,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1355,10 +1356,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1367,7 +1369,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1379,10 +1381,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1391,7 +1394,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1403,10 +1406,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1415,7 +1419,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64ADDconst)
@ -1427,10 +1431,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1439,7 +1444,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1451,10 +1456,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1463,7 +1469,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1475,10 +1481,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1487,7 +1494,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -1499,10 +1506,11 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
break
}
// match: (ADD a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (ADD <t> a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (ADD <v.Type> a m))
for {
t := v.Type
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
p := v_1
@ -1511,7 +1519,7 @@ func rewriteValueARM64_OpARM64ADD(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
continue
}
v.reset(OpARM64SUBconst)
@ -16604,10 +16612,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg3(a, x, y)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16615,7 +16624,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16625,10 +16634,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16636,7 +16646,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16646,10 +16656,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16657,7 +16668,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16667,10 +16678,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(ADDconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (SUBconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64ADDconst {
@ -16678,7 +16690,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64SUBconst)
@ -16688,10 +16700,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MUL _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16699,7 +16712,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MUL || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16709,10 +16722,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MULW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16720,7 +16734,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MULW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16730,10 +16744,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MNEG _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16741,7 +16756,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEG || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)
@ -16751,10 +16766,11 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
v.AddArg(v0)
return true
}
// match: (SUB a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1
// match: (SUB <t> a p:(SUBconst [c] m:(MNEGW _ _)))
// cond: p.Uses==1 && m.Uses==1 && !t.IsPtrShaped()
// result: (ADDconst [c] (SUB <v.Type> a m))
for {
t := v.Type
a := v_0
p := v_1
if p.Op != OpARM64SUBconst {
@ -16762,7 +16778,7 @@ func rewriteValueARM64_OpARM64SUB(v *Value) bool {
}
c := auxIntToInt64(p.AuxInt)
m := p.Args[0]
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1) {
if m.Op != OpARM64MNEGW || !(p.Uses == 1 && m.Uses == 1 && !t.IsPtrShaped()) {
break
}
v.reset(OpARM64ADDconst)

50
test/fixedbugs/issue71932.go Normal file
View File

@ -0,0 +1,50 @@
// run
// Copyright 2025 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 "runtime"
const C = 16
type T [C * C]byte
func main() {
var ts []*T
for i := 0; i < 100; i++ {
t := new(T)
// Save every even object.
if i%2 == 0 {
ts = append(ts, t)
}
}
// Make sure the odd objects are collected.
runtime.GC()
for _, t := range ts {
f(t, C, C)
}
}
//go:noinline
func f(t *T, i, j uint) {
if i == 0 || i > C || j == 0 || j > C {
return // gets rid of bounds check below (via prove pass)
}
p := &t[i*j-1]
*p = 0
runtime.GC()
*p = 0
// This goes badly if compiled to
// q := &t[i*j]
// *(q-1) = 0
// runtime.GC()
// *(q-1) = 0
// as at the GC call, q is an invalid pointer
// (it points past the end of t's allocation).
}