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cmd/compile: check for negative upper bound to IsSliceInBounds

Browse source 
IsSliceInBounds(x, y) asserts that y is not negative, but
there were cases where this is not true.  Change code
generation to ensure that this is true when it's not obviously
true.  Prove phase cleans a few of these out.

With this change the compiler text section is 0.06% larger,
that is, not very much.  Benchmarking still TBD, may need
to wait for access to a benchmarking box (next week).

Also corrected run.go to handle '?' in -update_errors output.

Fixes #28797.

Change-Id: Ia8af90bc50a91ae6e934ef973def8d3f398fac7b
Reviewed-on: https://go-review.googlesource.com/c/152477
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
David Chase 2018-12-04 10:00:16 -05:00
parent 179909f205
commit ea6259d5e9
5 changed files with 131 additions and 57 deletions
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21
src/cmd/compile/internal/gc/ssa.go
View file

@ -4022,6 +4022,18 @@ func (s *state) boundsCheck(idx, len *ssa.Value) {
s.check(cmp, panicindex)
}
func couldBeNegative(v *ssa.Value) bool {
switch v.Op {
case ssa.OpSliceLen, ssa.OpSliceCap, ssa.OpStringLen:
return false
case ssa.OpConst64:
return v.AuxInt < 0
case ssa.OpConst32:
return int32(v.AuxInt) < 0
}
return true
}
// sliceBoundsCheck generates slice bounds checking code. Checks if 0 <= idx <= len, branches to exit if not.
// Starts a new block on return.
// idx and len are already converted to full int width.
@ -4029,6 +4041,15 @@ func (s *state) sliceBoundsCheck(idx, len *ssa.Value) {
if Debug['B'] != 0 {
return
}
if couldBeNegative(len) {
// OpIsSliceInBounds requires second arg not negative; if it's not obviously true, must check.
cmpop := ssa.OpGeq64
if len.Type.Size() == 4 {
cmpop = ssa.OpGeq32
}
cmp := s.newValue2(cmpop, types.Types[TBOOL], len, s.zeroVal(len.Type))
s.check(cmp, panicslice)
}
// bounds check
cmp := s.newValue2(ssa.OpIsSliceInBounds, types.Types[TBOOL], idx, len)

53
test/fixedbugs/issue28797.go Normal file
View file

@ -0,0 +1,53 @@
// run
// Copyright 2018 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"
)
// test expects f to panic, but not to run out of memory,
// which is a non-panic fatal error. OOM results from failure
// to properly check negative limit.
func test(f func()) {
defer func() {
r := recover()
if r == nil {
panic("panic wasn't recoverable")
}
}()
f()
}
//go:noinline
func id(x int) int {
return x
}
func main() {
test(foo)
test(bar)
}
func foo() {
b := make([]byte, 0)
b = append(b, 1)
id(len(b))
id(len(b) - 2)
s := string(b[1 : len(b)-2])
fmt.Println(s)
}
func bar() {
b := make([]byte, 1)
b = append(b, 1)
i := id(-1)
if i < len(b) { // establish value is not too large.
s := string(b[1:i]) // should check for negative also.
fmt.Println(s)
}
}

94
test/loopbce.go
View file

@ -6,7 +6,7 @@ package main
func f0a(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
x += a[i] // ERROR "Proved IsInBounds$"
x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -14,7 +14,7 @@ func f0a(a []int) int {
func f0b(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
b := a[i:] // ERROR "Proved IsSliceInBounds$"
b := a[i:] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
x += b[0]
}
return x
@ -23,7 +23,7 @@ func f0b(a []int) int {
func f0c(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
b := a[:i+1] // ERROR "Proved IsSliceInBounds$"
b := a[:i+1] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
x += b[0]
}
return x
@ -40,7 +40,7 @@ func f1(a []int) int {
func f2(a []int) int {
x := 0
for i := 1; i < len(a); i++ { // ERROR "Induction variable: limits \[1,\?\), increment 1$"
x += a[i] // ERROR "Proved IsInBounds$"
x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -48,7 +48,7 @@ func f2(a []int) int {
func f4(a [10]int) int {
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,10\), increment 2$"
x += a[i] // ERROR "Proved IsInBounds$"
x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -63,7 +63,7 @@ func f5(a [10]int) int {
func f6(a []int) {
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
b := a[0:i] // ERROR "Proved IsSliceInBounds$"
b := a[0:i] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$" "(\([0-9]+\) )?Proved Geq64$"
f6(b)
}
}
@ -71,7 +71,7 @@ func f6(a []int) {
func g0a(a string) int {
x := 0
for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
x += int(a[i]) // ERROR "Proved IsInBounds$"
x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -79,7 +79,7 @@ func g0a(a string) int {
func g0b(a string) int {
x := 0
for i := 0; len(a) > i; i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
x += int(a[i]) // ERROR "Proved IsInBounds$"
x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -87,7 +87,7 @@ func g0b(a string) int {
func g0c(a string) int {
x := 0
for i := len(a); i > 0; i-- { // ERROR "Induction variable: limits \(0,\?\], increment 1$"
x += int(a[i-1]) // ERROR "Proved IsInBounds$"
x += int(a[i-1]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -95,7 +95,7 @@ func g0c(a string) int {
func g0d(a string) int {
x := 0
for i := len(a); 0 < i; i-- { // ERROR "Induction variable: limits \(0,\?\], increment 1$"
x += int(a[i-1]) // ERROR "Proved IsInBounds$"
x += int(a[i-1]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -103,7 +103,7 @@ func g0d(a string) int {
func g0e(a string) int {
x := 0
for i := len(a) - 1; i >= 0; i-- { // ERROR "Induction variable: limits \[0,\?\], increment 1$"
x += int(a[i]) // ERROR "Proved IsInBounds$"
x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -111,7 +111,7 @@ func g0e(a string) int {
func g0f(a string) int {
x := 0
for i := len(a) - 1; 0 <= i; i-- { // ERROR "Induction variable: limits \[0,\?\], increment 1$"
x += int(a[i]) // ERROR "Proved IsInBounds$"
x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -120,7 +120,7 @@ func g1() int {
a := "evenlength"
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,10\), increment 2$"
x += int(a[i]) // ERROR "Proved IsInBounds$"
x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return x
}
@ -130,7 +130,7 @@ func g2() int {
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,10\), increment 2$"
j := i
if a[i] == 'e' { // ERROR "Proved IsInBounds$"
if a[i] == 'e' { // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
j = j + 1
}
x += int(a[j])
@ -141,27 +141,27 @@ func g2() int {
func g3a() {
a := "this string has length 25"
for i := 0; i < len(a); i += 5 { // ERROR "Induction variable: limits \[0,25\), increment 5$"
useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useString(a[:i+3])
}
}
func g3b(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[i+1:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i+1:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
}
func g3c(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[:i+1]) // ERROR "Proved IsSliceInBounds$"
useString(a[:i+1]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
}
func h1(a []byte) {
c := a[:128]
for i := range c { // ERROR "Induction variable: limits \[0,128\), increment 1$"
c[i] = byte(i) // ERROR "Proved IsInBounds$"
c[i] = byte(i) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
}
@ -174,11 +174,11 @@ func h2(a []byte) {
func k0(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable: limits \[10,90\), increment 1$"
a[i-11] = i
a[i-10] = i // ERROR "Proved IsInBounds$"
a[i-5] = i // ERROR "Proved IsInBounds$"
a[i] = i // ERROR "Proved IsInBounds$"
a[i+5] = i // ERROR "Proved IsInBounds$"
a[i+10] = i // ERROR "Proved IsInBounds$"
a[i-10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i-5] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+5] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+11] = i
}
return a
@ -186,13 +186,13 @@ func k0(a [100]int) [100]int {
func k1(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable: limits \[10,90\), increment 1$"
useSlice(a[:i-11])
useSlice(a[:i-10]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i-5]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i+5]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i+10]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i+11]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i-11]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i-10]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i-5]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$" "(\([0-9]+\) )?Proved Geq64$"
useSlice(a[:i+5]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i+10]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i+11]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[:i+12])
}
@ -202,12 +202,12 @@ func k1(a [100]int) [100]int {
func k2(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable: limits \[10,90\), increment 1$"
useSlice(a[i-11:])
useSlice(a[i-10:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i-5:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i+5:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i+10:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i+11:]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[i-10:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i-5:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i+5:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i+10:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i+11:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
useSlice(a[i+12:])
}
return a
@ -216,7 +216,7 @@ func k2(a [100]int) [100]int {
func k3(a [100]int) [100]int {
for i := -10; i < 90; i++ { // ERROR "Induction variable: limits \[-10,90\), increment 1$"
a[i+9] = i
a[i+10] = i // ERROR "Proved IsInBounds$"
a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+11] = i
}
return a
@ -225,7 +225,7 @@ func k3(a [100]int) [100]int {
func k3neg(a [100]int) [100]int {
for i := 89; i > -11; i-- { // ERROR "Induction variable: limits \(-11,89\], increment 1$"
a[i+9] = i
a[i+10] = i // ERROR "Proved IsInBounds$"
a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+11] = i
}
return a
@ -234,7 +234,7 @@ func k3neg(a [100]int) [100]int {
func k3neg2(a [100]int) [100]int {
for i := 89; i >= -10; i-- { // ERROR "Induction variable: limits \[-10,89\], increment 1$"
a[i+9] = i
a[i+10] = i // ERROR "Proved IsInBounds$"
a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i+11] = i
}
return a
@ -243,16 +243,16 @@ func k3neg2(a [100]int) [100]int {
func k4(a [100]int) [100]int {
min := (-1) << 63
for i := min; i < min+50; i++ { // ERROR "Induction variable: limits \[-9223372036854775808,-9223372036854775758\), increment 1$"
a[i-min] = i // ERROR "Proved IsInBounds$"
a[i-min] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return a
}
func k5(a [100]int) [100]int {
max := (1 << 63) - 1
for i := max - 50; i < max; i++ { // ERROR "Induction variable: limits \[9223372036854775757,9223372036854775807\), increment 1"
a[i-max+50] = i // ERROR "Proved IsInBounds$"
a[i-(max-70)] = i // ERROR "Proved IsInBounds$"
for i := max - 50; i < max; i++ { // ERROR "Induction variable: limits \[9223372036854775757,9223372036854775807\), increment 1$"
a[i-max+50] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
a[i-(max-70)] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
}
return a
}
@ -275,17 +275,17 @@ func nobce1() {
func nobce2(a string) {
for i := int64(0); i < int64(len(a)); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))-31337; i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
j := int64(len(a)) - 123
for i := int64(0); i < j+123+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
}
for i := int64(0); i < j+122+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
// len(a)-123+122+MinInt overflows when len(a) == 0, so a bound check is needed here

18
test/prove.go
View file

@ -62,7 +62,7 @@ func f1c(a []int, i int64) int {
}
func f2(a []int) int {
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1"
for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
a[i+1] = i
a[i+1] = i // ERROR "Proved IsInBounds$"
}
@ -269,7 +269,7 @@ func f11b(a []int, i int) {
func f11c(a []int, i int) {
useSlice(a[:i])
useSlice(a[:i]) // ERROR "Proved IsSliceInBounds$"
useSlice(a[:i]) // ERROR "Proved Geq64$" "Proved IsSliceInBounds$"
}
func f11d(a []int, i int) {
@ -464,12 +464,12 @@ func f16(s []int) []int {
}
func f17(b []int) {
for i := 0; i < len(b); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1"
for i := 0; i < len(b); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
// This tests for i <= cap, which we can only prove
// using the derived relation between len and cap.
// This depends on finding the contradiction, since we
// don't query this condition directly.
useSlice(b[:i]) // ERROR "Proved IsSliceInBounds$"
useSlice(b[:i]) // ERROR "Proved Geq64$" "Proved IsSliceInBounds$"
}
}
@ -579,18 +579,18 @@ func fence4(x, y int64) {
func trans1(x, y int64) {
if x > 5 {
if y > x {
if y > 2 { // ERROR "Proved Greater64"
if y > 2 { // ERROR "Proved Greater64$"
return
}
} else if y == x {
if y > 5 { // ERROR "Proved Greater64"
if y > 5 { // ERROR "Proved Greater64$"
return
}
}
}
if x >= 10 {
if y > x {
if y > 10 { // ERROR "Proved Greater64"
if y > 10 { // ERROR "Proved Greater64$"
return
}
}
@ -624,7 +624,7 @@ func natcmp(x, y []uint) (r int) {
}
i := m - 1
for i > 0 && // ERROR "Induction variable: limits \(0,\?\], increment 1"
for i > 0 && // ERROR "Induction variable: limits \(0,\?\], increment 1$"
x[i] == // ERROR "Proved IsInBounds$"
y[i] { // ERROR "Proved IsInBounds$"
i--
@ -686,7 +686,7 @@ func range2(b [][32]int) {
if i < len(b) { // ERROR "Proved Less64$"
println("x")
}
if i >= 0 { // ERROR "Proved Geq64"
if i >= 0 { // ERROR "Proved Geq64$"
println("x")
}
}

2
test/run.go
View file

@ -1212,7 +1212,7 @@ func (t *test) updateErrors(out, file string) {
msg := errStr[colon2+2:]
msg = strings.Replace(msg, file, base, -1) // normalize file mentions in error itself
msg = strings.TrimLeft(msg, " \t")
for _, r := range []string{`\`, `*`, `+`, `[`, `]`, `(`, `)`} {
for _, r := range []string{`\`, `*`, `+`, `?`, `[`, `]`, `(`, `)`} {
msg = strings.Replace(msg, r, `\`+r, -1)
}
msg = strings.Replace(msg, `"`, `.`, -1)