encoding/json: unexpected fault address 0x26000000c6

[nzlov]

What version of Go are you using (go version)?

$ go version
go version go1.15.5 darwin/amd64

Does this issue reproduce with the latest release?

Yes, but 1.14.2 is work.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/mac/Library/Caches/go-build"
GOENV="/Users/mac/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/mac/workspace/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/mac/workspace/go"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/Users/mac/program/go"
GOSUMDB=""
GOTMPDIR=""
GOTOOLDIR="/Users/mac/program/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/mac/program/go/src/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/y7/wj_j6jds1j7bz0bvp_bz1kf00000gn/T/go-build694457940=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

	a := A{}
	m := map[string]interface{}{}
	d, _ := json.Marshal(a)
	json.Unmarshal(d, &m)

Compile docker for linux on macos and run it on k8s

What did you expect to see?

Parse data to map

What did you see instead?

unexpected fault address 0x26000000c6
fatal error: fault
[signal SIGSEGV: segmentation violation code=0x1 addr=0x26000000c6 pc=0x52445d]

goroutine 93 [running]:
runtime.throw(0x1178d74, 0x5)
	/Users/mac/program/go/src/runtime/panic.go:1116 +0x72 fp=0xc00064d768 sp=0xc00064d738 pc=0x437752
runtime.sigpanic()
	/Users/mac/program/go/src/runtime/signal_unix.go:749 +0x405 fp=0xc00064d798 sp=0xc00064d768 pc=0x44dae5
encoding/json.(*encodeState).string(0xc00055e300, 0x26000000c6, 0x102000000c1, 0x2600000001)
	/Users/mac/program/go/src/encoding/json/encode.go:1004 +0x5d fp=0xc00064d7f8 sp=0xc00064d798 pc=0x52445d
encoding/json.stringEncoder(0xc00055e300, 0xfc68c0, 0xc000512d00, 0x98, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:645 +0x1d6 fp=0xc00064d878 sp=0xc00064d7f8 pc=0x521896
encoding/json.structEncoder.encode(0xc0006dd800, 0x22, 0x43, 0xc000597590, 0xc00055e300, 0x1166c40, 0xc000512b38, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:759 +0x2ab fp=0xc00064d910 sp=0xc00064d878 pc=0x52220b
encoding/json.structEncoder.encode-fm(0xc00055e300, 0x1166c40, 0xc000512b38, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:730 +0x7f fp=0xc00064d968 sp=0xc00064d910 pc=0x52eb9f
encoding/json.structEncoder.encode(0xc0006a8600, 0x3b, 0x43, 0xc00059a150, 0xc00055e300, 0x11733c0, 0xc0005126a0, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:759 +0x2ab fp=0xc00064da00 sp=0xc00064d968 pc=0x52220b
encoding/json.structEncoder.encode-fm(0xc00055e300, 0x11733c0, 0xc0005126a0, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:730 +0x7f fp=0xc00064da58 sp=0xc00064da00 pc=0x52eb9f
encoding/json.structEncoder.encode(0xc0006db200, 0x23, 0x43, 0xc00059a1b0, 0xc00055e300, 0x1167360, 0xc0005122c8, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:759 +0x2ab fp=0xc00064daf0 sp=0xc00064da58 pc=0x52220b
encoding/json.structEncoder.encode-fm(0xc00055e300, 0x1167360, 0xc0005122c8, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:730 +0x7f fp=0xc00064db48 sp=0xc00064daf0 pc=0x52eb9f
encoding/json.structEncoder.encode(0xc00084a000, 0x20, 0x21, 0xc00059b2c0, 0xc00055e300, 0x11643a0, 0xc000511a60, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:759 +0x2ab fp=0xc00064dbe0 sp=0xc00064db48 pc=0x52220b
encoding/json.structEncoder.encode-fm(0xc00055e300, 0x11643a0, 0xc000511a60, 0x99, 0x100)
	/Users/mac/program/go/src/encoding/json/encode.go:730 +0x7f fp=0xc00064dc38 sp=0xc00064dbe0 pc=0x52eb9f
encoding/json.structEncoder.encode(0xc0006ce400, 0xd, 0x10, 0xc00059b320, 0xc00055e300, 0x11367c0, 0xc00050e000, 0x99, 0x1130100)
	/Users/mac/program/go/src/encoding/json/encode.go:759 +0x2ab fp=0xc00064dcd0 sp=0xc00064dc38 pc=0x52220b
encoding/json.structEncoder.encode-fm(0xc00055e300, 0x11367c0, 0xc00050e000, 0x99, 0x1c20100)
	/Users/mac/program/go/src/encoding/json/encode.go:730 +0x7f fp=0xc00064dd28 sp=0xc00064dcd0 pc=0x52eb9f
encoding/json.(*encodeState).reflectValue(0xc00055e300, 0x11367c0, 0xc00050e000, 0x99, 0xc000640100)
	/Users/mac/program/go/src/encoding/json/encode.go:358 +0x82 fp=0xc00064dd60 sp=0xc00064dd28 pc=0x51f902
encoding/json.(*encodeState).marshal(0xc00055e300, 0x11367c0, 0xc00050e000, 0xc000640100, 0x0, 0x0)
	/Users/mac/program/go/src/encoding/json/encode.go:330 +0xf4 fp=0xc00064ddc0 sp=0xc00064dd60 pc=0x51f4f4
encoding/json.Marshal(0x11367c0, 0xc00050e000, 0xc000125020, 0x203000, 0x203000, 0x203000, 0x0)
	/Users/mac/program/go/src/encoding/json/encode.go:161 +0x52 fp=0xc00064de38 sp=0xc00064ddc0 pc=0x51e972

[davecheney]

Thank you for raising this issue. Your sample code looks incomplete as the stack trace you included mentioned goroutine 93 whereas the code fragment you provided did not use goroutines.

Can you please

1. Provide a runnable code sample and steps to reproduce the issue you see.
2. Please compile and deploy your application with the race detector and confirm that there are no data races present.

[nzlov]

@davecheney
No data race.
Demo needs to wait.

[mvdan]

Line 1004 in question is if b := s[i]; b < utf8.RuneSelf {, so this is certainly not a bug in json.

Without a reproducer or more details, there's not much we can do here.

[xtutu]

hi, @nzlov I met the same issuse.
Do you solve it?

[davecheney]

@xtutu please log a new issue and be sure to complete the entire template. You must provide a way for someone else to reproduce the problem you are seeing.

[xtutu]

@davecheney , i found what happy in my code . it solved.
valueList is data race.

import (
        "encoding/json"
        "fmt"
        "testing"
        "time"
)
func TestABC(t *testing.T) {
        type FF struct {
                EE map[string][]string
        }

        a := make(map[string][]string)
        for i := 0; i < 10000; i++ {
                list := make([]string, 0)
                for j := 0; j < (i % 10) + 1; j++ {
                        list = append(list, "1")
                }
                a[fmt.Sprintf("%d", i)] = list
        }

        // wrong code!
        // this will failed
        for _, valueList := range a {
                go func() {
                        ff := &FF{EE: make(map[string][]string)}
                        ff.EE["x"] = valueList
                        _, _ = json.Marshal(ff)
                }()
        }
        
        // right code!
        // this is ok
        // for _, valueList := range a {
        //       tmpValueList := valueList
        //         go func() {
        //                 ff := &FF{EE: make(map[string][]string)}
        //                 ff.EE["x"] = tmpValueList
        //                 _, _ = json.Marshal(ff)
        //         }()
        // }
        
        time.Sleep(time.Second * 20)
}

[davecheney]

Thank you. I am closing and resolving this issue.