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35e6a10c90
Consider the following code:
func f(x []*T) interface{} {
return x
}
It returns an interface that holds a heap copy of x (by calling
convT2I or friend), therefore x escape to heap. The current
escape analysis only recognizes that x flows to the result. This
is not sufficient, since if the result does not escape, x's
content may be stack allocated and this will result a
heap-to-stack pointer, which is bad.
Fix this by realizing that if a CONVIFACE escapes and we're
converting from a non-direct interface type, the data needs to
escape to heap.
Running "toolstash -cmp" on std & cmd, the generated machine code
are identical for all packages. However, the export data (escape
tags) differ in the following packages. It looks to me that all
are similar to the "f" above, where the parameter should escape
to heap.
io/ioutil/ioutil.go:118
old: leaking param: r to result ~r1 level=0
new: leaking param: r
image/image.go:943
old: leaking param: p to result ~r0 level=1
new: leaking param content: p
net/url/url.go:200
old: leaking param: s to result ~r2 level=0
new: leaking param: s
(as a consequence)
net/url/url.go:183
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:194
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:699
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:775
old: (*URL).String u does not escape
new: leaking param content: u
net/url/url.go:1038
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:1099
old: (*URL).MarshalBinary u does not escape
new: leaking param content: u
flag/flag.go:235
old: leaking param: s to result ~r0 level=1
new: leaking param content: s
go/scanner/errors.go:105
old: leaking param: p to result ~r0 level=0
new: leaking param: p
database/sql/sql.go:204
old: leaking param: ns to result ~r0 level=0
new: leaking param: ns
go/constant/value.go:303
old: leaking param: re to result ~r2 level=0, leaking param: im to result ~r2 level=0
new: leaking param: re, leaking param: im
go/constant/value.go:846
old: leaking param: x to result ~r1 level=0
new: leaking param: x
encoding/xml/xml.go:518
old: leaking param: d to result ~r1 level=2
new: leaking param content: d
encoding/xml/xml.go:122
old: leaking param: leaking param: t to result ~r1 level=0
new: leaking param: t
crypto/x509/verify.go:506
old: leaking param: c to result ~r8 level=0
new: leaking param: c
crypto/x509/verify.go:563
old: leaking param: c to result ~r3 level=0, leaking param content: c
new: leaking param: c
crypto/x509/verify.go:615
old: (nothing)
new: leaking closure reference c
crypto/x509/verify.go:996
old: leaking param: c to result ~r1 level=0, leaking param content: c
new: leaking param: c
net/http/filetransport.go:30
old: leaking param: fs to result ~r1 level=0
new: leaking param: fs
net/http/h2_bundle.go:2684
old: leaking param: mh to result ~r0 level=2
new: leaking param content: mh
net/http/h2_bundle.go:7352
old: http2checkConnHeaders req does not escape
new: leaking param content: req
net/http/pprof/pprof.go:221
old: leaking param: name to result ~r1 level=0
new: leaking param: name
cmd/internal/bio/must.go:21
old: leaking param: w to result ~r1 level=0
new: leaking param: w
Fixes #29353.
Change-Id: I7e7798ae773728028b0dcae5bccb3ada51189c68
Reviewed-on: https://go-review.googlesource.com/c/162829
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Chase <drchase@google.com>
(cherry picked from commit 0349f29a55
)
Reviewed-on: https://go-review.googlesource.com/c/163203
Reviewed-by: Ian Lance Taylor <iant@golang.org>
210 lines
8.6 KiB
Go
210 lines
8.6 KiB
Go
// errorcheck -0 -m -m -l
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Note the doubled -m; this tests the "because" explanations for escapes,
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// and is likely to be annoyingly fragile under compiler change.
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// As long as the explanations look reasonably sane, meaning eyeball verify output of
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// go build -gcflags '-l -m -m' escape_because.go
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// and investigate changes, feel free to update with
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// go run run.go -update_errors -- escape_because.go
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package main
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func main() {
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}
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var sink interface{}
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type pair struct {
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x, y *int
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}
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type Pairy interface {
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EqualParts() bool
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}
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func (p *pair) EqualParts() bool { // ERROR "\(\*pair\).EqualParts p does not escape$"
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return p != nil && (p.x == p.y || *p.x == *p.y)
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}
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func f1(p *int) { // ERROR "from \[3\]\*int literal \(array literal element\) at escape_because.go:34$" "from a \(assigned\) at escape_because.go:34$" "from a \(interface-converted\) at escape_because.go:35$" "from sink \(assigned to top level variable\) at escape_because.go:35$" "leaking param: p$"
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a := [3]*int{p, nil, nil}
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sink = a // ERROR "a escapes to heap$" "from sink \(assigned to top level variable\) at escape_because.go:35$"
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}
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func f2(q *int) { // ERROR "from &u \(address-of\) at escape_because.go:43$" "from &u \(interface-converted\) at escape_because.go:43$" "from pair literal \(struct literal element\) at escape_because.go:41$" "from s \(assigned\) at escape_because.go:40$" "from sink \(assigned to top level variable\) at escape_because.go:43$" "from t \(assigned\) at escape_because.go:41$" "from u \(assigned\) at escape_because.go:42$" "leaking param: q$"
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s := q
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t := pair{s, nil}
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u := t // ERROR "moved to heap: u$"
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sink = &u // ERROR "&u escapes to heap$" "from &u \(interface-converted\) at escape_because.go:43$" "from sink \(assigned to top level variable\) at escape_because.go:43$"
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}
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func f3(r *int) interface{} { // ERROR "from \[\]\*int literal \(slice-literal-element\) at escape_because.go:47$" "from c \(assigned\) at escape_because.go:47$" "from c \(interface-converted\) at escape_because.go:48$" "from ~r1 \(return\) at escape_because.go:48$" "leaking param: r"
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c := []*int{r} // ERROR "\[\]\*int literal escapes to heap$" "from c \(assigned\) at escape_because.go:47$" "from c \(interface-converted\) at escape_because.go:48$" "from ~r1 \(return\) at escape_because.go:48$"
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return c // "return" // ERROR "c escapes to heap$" "from ~r1 \(return\) at escape_because.go:48$"
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}
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func f4(a *int, s []*int) int { // ERROR "from \*s \(indirection\) at escape_because.go:51$" "from append\(s, a\) \(appended to slice\) at escape_because.go:52$" "from append\(s, a\) \(appendee slice\) at escape_because.go:52$" "leaking param content: s$" "leaking param: a$"
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s = append(s, a)
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return *(s[0])
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}
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func f5(s1, s2 []*int) int { // ERROR "from \*s1 \(indirection\) at escape_because.go:56$" "from \*s2 \(indirection\) at escape_because.go:56$" "from append\(s1, s2...\) \(appended slice...\) at escape_because.go:57$" "from append\(s1, s2...\) \(appendee slice\) at escape_because.go:57$" "leaking param content: s1$" "leaking param content: s2$"
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s1 = append(s1, s2...)
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return *(s1[0])
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}
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func f6(x, y *int) bool { // ERROR "f6 x does not escape$" "f6 y does not escape$"
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p := pair{x, y}
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var P Pairy = &p // ERROR "f6 &p does not escape$"
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pp := P.(*pair)
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return pp.EqualParts()
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}
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func f7(x map[int]*int, y int) *int { // ERROR "f7 x does not escape$"
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z, ok := x[y]
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if !ok {
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return nil
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}
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return z
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}
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func f8(x int, y *int) *int { // ERROR "from ~r2 \(return\) at escape_because.go:78$" "from ~r2 \(returned from recursive function\) at escape_because.go:76$" "leaking param: y$" "moved to heap: x$"
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if x <= 0 {
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return y
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}
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x--
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return f8(*y, &x) // ERROR "&x escapes to heap$" "from y \(arg to recursive call\) at escape_because.go:81$" "from ~r2 \(return\) at escape_because.go:78$" "from ~r2 \(returned from recursive function\) at escape_because.go:76$"
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}
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func f9(x int, y ...*int) *int { // ERROR "from y\[0\] \(dot of pointer\) at escape_because.go:86$" "from ~r2 \(return\) at escape_because.go:86$" "from ~r2 \(returned from recursive function\) at escape_because.go:84$" "leaking param content: y$" "leaking param: y to result ~r2 level=1$" "moved to heap: x$"
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if x <= 0 {
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return y[0]
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}
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x--
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return f9(*y[0], &x) // ERROR "&x escapes to heap$" "f9 ... argument does not escape$" "from ... argument \(... arg to recursive call\) at escape_because.go:89$"
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}
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func f10(x map[*int]*int, y, z *int) *int { // ERROR "f10 x does not escape$" "from x\[y\] \(key of map put\) at escape_because.go:93$" "from x\[y\] \(value of map put\) at escape_because.go:93$" "leaking param: y$" "leaking param: z$"
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x[y] = z
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return z
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}
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func f11(x map[*int]*int, y, z *int) map[*int]*int { // ERROR "f11 x does not escape$" "from map\[\*int\]\*int literal \(map literal key\) at escape_because.go:98$" "from map\[\*int\]\*int literal \(map literal value\) at escape_because.go:98$" "leaking param: y$" "leaking param: z$"
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return map[*int]*int{y: z} // ERROR "from ~r3 \(return\) at escape_because.go:98$" "map\[\*int\]\*int literal escapes to heap$"
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}
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func f12() {
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b := []byte("test") // ERROR "\(\[\]byte\)\(.test.\) escapes to heap$" "from b \(assigned\) at escape_because.go:102$" "from b \(passed to call\[argument escapes\]\) at escape_because.go:103$"
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escape(b)
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}
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func escape(b []byte) { // ERROR "from panic\(b\) \(panic\) at escape_because.go:107$" "leaking param: b$"
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panic(b)
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}
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func f13() {
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b := []byte("test") // ERROR "\(\[\]byte\)\(.test.\) escapes to heap$" "from .out0 \(passed-to-and-returned-from-call\) at escape_because.go:112$" "from b \(assigned\) at escape_because.go:111$" "from c \(assigned\) at escape_because.go:112$" "from c \(passed to call\[argument escapes\]\) at escape_because.go:113$"
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c := transmit(b)
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escape(c)
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}
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func transmit(b []byte) []byte { // ERROR "from ~r1 \(return\) at escape_because.go:117$" "leaking param: b to result ~r1 level=0$"
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return b
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}
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func f14() {
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n := 32
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s1 := make([]int, n) // ERROR "make\(\[\]int, n\) escapes to heap" "from make\(\[\]int, n\) \(non-constant size\)"
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s2 := make([]int, 0, n) // ERROR "make\(\[\]int, 0, n\) escapes to heap" "from make\(\[\]int, 0, n\) \(non-constant size\)"
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_, _ = s1, s2
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}
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func leakParams(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2 level=0$" "from ~r2 \(return\) at escape_because.go:128$" "leaking param: p2 to result ~r3 level=0$" "from ~r3 \(return\) at escape_because.go:128$"
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return p1, p2
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}
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func leakThroughOAS2() {
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// See #26987.
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i := 0 // ERROR "moved to heap: i$"
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j := 0 // ERROR "moved to heap: j$"
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sink, sink = &i, &j // ERROR "&i escapes to heap$" "from sink \(assign-pair\) at escape_because.go:135$" "from &i \(interface-converted\) at escape_because.go:135$" "&j escapes to heap$" "from &j \(interface-converted\) at escape_because.go:135"
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}
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func leakThroughOAS2FUNC() {
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// See #26987.
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i := 0 // ERROR "moved to heap: i$"
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j := 0
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sink, _ = leakParams(&i, &j) // ERROR "&i escapes to heap$" "&j does not escape$" "from .out0 \(passed-to-and-returned-from-call\) at escape_because.go:142$" "from sink \(assign-pair-func-call\) at escape_because.go:142$"
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}
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// The list below is all of the why-escapes messages seen building the escape analysis tests.
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/*
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for i in escape*go ; do echo compile $i; go build -gcflags '-l -m -m' $i >& `basename $i .go`.log ; done
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grep 'from .* at ' escape*.log | sed -e 's/^.*(\([^()]*\))[^()]*$/\1/' | sort -u
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*/
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// sed RE above assumes that (reason) is the last parenthesized phrase in the line,
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// and that none of the reasons contains any parentheses
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/*
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... arg to recursive call
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address-of
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appended slice...
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appended to slice
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appendee slice
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arg to ...
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arg to recursive call
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array-element-equals
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array literal element
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assigned
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assigned to top level variable
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assign-pair-dot-type
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assign-pair-func-call
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captured by a closure
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captured by called closure
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dot
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dot-equals
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dot of pointer
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fixed-array-index-of
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go func arg
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indirection
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interface-converted
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key of map put
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map literal key
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map literal value
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non-constant size
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panic
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parameter to indirect call
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passed-to-and-returned-from-call
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passed to call[argument content escapes]
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passed to call[argument escapes]
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pointer literal
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range-deref
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receiver in indirect call
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return
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returned from recursive function
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slice-element-equals
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slice-literal-element
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star-dot-equals
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star-equals
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struct literal element
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too large for stack
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value of map put
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*/
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// Expected, but not yet seen (they may be unreachable):
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/*
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append-first-arg
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assign-pair-mapr
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assign-pair-receive
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call receiver
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map index
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pointer literal [assign]
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slice literal element
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*/
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