plugin: using same type in map across two plugins causes stackoverflow #19258

vimalk78 · 2017-02-23T13:17:59Z

Please answer these questions before submitting your issue. Thanks!

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

$ go version
go version go1.8 linux/amd64

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

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/vimal/gowork"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build121316025=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

using the plugins feature. created the following two plugins using the command go build -buildmode=plugin

plugin1

package main

import "C"
import "log"

func init() {
    log.Printf("testplugin.main.init invoked\n")
}

type innerType struct {
    f1 int
    f2 string
}

type MyStruct struct {
    Name string
    Id   int
    mm   map[string]innerType
}

func InitPlugin() {
    m := MyStruct{Name: "x", Id: 0}
    log.Printf("testplugin.InitPlugin %v", m)
}

plugin2

package main

import "C"
import "log"

func init() {
    log.Printf("testplugin1.main.init invoked\n")
}

type innerType struct {
    f1 int
    f2 string
}

type MyStruct struct {
    Name string
    Id   int
    mm   map[string]innerType
}

func InitPlugin() {
    m := MyStruct{Name: "x", Id: 0}
    log.Printf("testplugin1.InitPlugin %v", m)
}

Both plugins have the same code, except the minor difference in print statements.

a main program loads the plugins using the api plugin.Open(pluginpath)

What did you expect to see?

Both plugins loaded succesfully.

What did you see instead?

a stackoverflow error. I have limited the stack using debug.SetMaxStack(100) so that i can see the beginning of the stack.

runtime: goroutine stack exceeds 100-byte limit
fatal error: stack overflow

runtime stack:
runtime.throw(0x537589, 0xe)
        /usr/local/go/src/runtime/panic.go:596 +0x95
runtime.newstack(0x0)
        /usr/local/go/src/runtime/stack.go:1089 +0x3f2
runtime.morestack()
        /usr/local/go/src/runtime/asm_amd64.s:398 +0x86

goroutine 1 [running]:
runtime.(*_type).string(0x7f29a2dca140, 0x0, 0x0)
        /usr/local/go/src/runtime/type.go:45 +0xad fp=0xc42004c320 sp=0xc42004c318
runtime.typesEqual(0x7f29a2dca140, 0x7f29a31de140, 0x0)
        /usr/local/go/src/runtime/type.go:543 +0x73 fp=0xc42004c448 sp=0xc42004c320
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004c570 sp=0xc42004c448
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004c698 sp=0xc42004c570
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004c7c0 sp=0xc42004c698
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004c8e8 sp=0xc42004c7c0
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004ca10 sp=0xc42004c8e8
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004cb38 sp=0xc42004ca10
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004cc60 sp=0xc42004cb38
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004cd88 sp=0xc42004cc60
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004ceb0 sp=0xc42004cd88
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004cfd8 sp=0xc42004ceb0
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004d100 sp=0xc42004cfd8
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004d228 sp=0xc42004d100
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004d350 sp=0xc42004d228
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004d478 sp=0xc42004d350
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004d5a0 sp=0xc42004d478
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0x0)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004d6c8 sp=0xc42004d5a0
runtime.typesEqual(0x7f29a2dd4a60, 0x7f29a31e8a60, 0x7f29a31d2850)
        /usr/local/go/src/runtime/type.go:647 +0xc0a fp=0xc42004d7f0 sp=0xc42004d6c8
runtime.typesEqual(0x7f29a2dc0a60, 0x7f29a31d4a60, 0xc4800c6242)
        /usr/local/go/src/runtime/type.go:627 +0x9c5 fp=0xc42004d918 sp=0xc42004d7f0
runtime.typelinksinit()
        /usr/local/go/src/runtime/type.go:510 +0x432 fp=0xc42004db20 sp=0xc42004d918
plugin.lastmoduleinit(0xc39400, 0xc42000fb48, 0xc3ab60, 0x43, 0x7bbf60)
        /usr/local/go/src/runtime/plugin.go:52 +0x2f9 fp=0xc42004dc50 sp=0xc42004db20
plugin.open(0x7fffaaddfd48, 0x1d, 0x0, 0x0, 0x0)
        /usr/local/go/src/plugin/plugin_dlopen.go:72 +0x25d fp=0xc42004de90 sp=0xc42004dc50
plugin.Open(0x7fffaaddfd48, 0x1d, 0xc42004df28, 0x1, 0x1)
        /usr/local/go/src/plugin/plugin.go:30 +0x35 fp=0xc42004dec8 sp=0xc42004de90
main.loadPlugin(0x7fffaaddfd48, 0x1d, 0xc42000c200)
        /home/vimal/gowork/src/github.com/v70420/pluginfw/main.go:31 +0xd7 fp=0xc42004df48 sp=0xc42004dec8
main.main()
        /home/vimal/gowork/src/github.com/v70420/pluginfw/main.go:19 +0x75 fp=0xc42004df88 sp=0xc42004df48
runtime.main()
        /usr/local/go/src/runtime/proc.go:185 +0x20a fp=0xc42004dfe0 sp=0xc42004df88
runtime.goexit()
        /usr/local/go/src/runtime/asm_amd64.s:2197 +0x1 fp=0xc42004dfe8 sp=0xc42004dfe0

without limiting the stack size, the error is same, except

runtime: goroutine stack exceeds 1000000000-byte limit
fatal error: stack overflow

i narrowed down the issue to this

type MyStruct struct {
    Name string
    Id   int
    mm   map[string]innerType << using the type in map causes the error
}

If the type is not used in the map, the error is gone, and both plugins can be loaded successfully.

type MyStruct struct {
    Name string
    Id   int
    // mm   map[string]innerType << commenting this line does not cause the error
}

also, renaming the type innerType to some other name, say, innerType_xyz in one of the plugins also avoids the stackoverflow.

The text was updated successfully, but these errors were encountered:

tzneal · 2017-04-11T02:36:21Z

It's walking an infinite list of types caused by the overflow buckets in the map. Each bucket has a has a values field of type innerType, and a pointer to a bucket. Since everything else is identical, it recurses through the bucket pointer back to a bucket, and keeps going.

Any identical recursive type definition in two plugins causes it.

gopherbot · 2017-04-11T03:01:11Z

CL https://golang.org/cl/40292 mentions this issue.

vimalk78 · 2017-04-11T05:32:49Z

not sure, but does it make sense to check reverse way also?

	tp := _typePair{t, v}
	if _, ok := seen[tp]; ok {
		return true
	}
        reversetp := _typePair{v, t}
	if _, ok := seen[reversetp]; ok {
		return true
	}

        ...
        ...
        seen[tp] = struct{}{}
        seen[reversetp] = struct{}{}

Prevent a crash if the same type in two plugins had a recursive definition, either by referring to a pointer to itself or a map existing with the type as a value type (which creates a recursive definition through the overflow bucket type). Fixes golang#19258 Change-Id: Iac1cbda4c5b6e8edd5e6859a4d5da3bad539a9c6 Reviewed-on: https://go-review.googlesource.com/40292 Run-TryBot: Todd Neal <todd@tneal.org> Reviewed-by: David Crawshaw <crawshaw@golang.org>

vimalk78 changed the title ~~plugin: using same type in map causes stackoverflow~~ plugin: using same type in map across two plugins causes stackoverflow Feb 23, 2017

ianlancetaylor added this to the Go1.9 milestone Feb 23, 2017

ianlancetaylor assigned crawshaw Feb 23, 2017

vimalk78 mentioned this issue Apr 5, 2017

plugin: opening plugin built with -linkshared flag results in stackoverflow #19852

Closed

gopherbot closed this as completed in e49627d Apr 12, 2017

golang locked and limited conversation to collaborators Apr 12, 2018

gopherbot unassigned crawshaw Apr 12, 2018

gopherbot added the FrozenDueToAge label Apr 12, 2018

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plugin: using same type in map across two plugins causes stackoverflow #19258

plugin: using same type in map across two plugins causes stackoverflow #19258

vimalk78 commented Feb 23, 2017 •

edited

tzneal commented Apr 11, 2017

gopherbot commented Apr 11, 2017

vimalk78 commented Apr 11, 2017

plugin: using same type in map across two plugins causes stackoverflow #19258

plugin: using same type in map across two plugins causes stackoverflow #19258

Comments

vimalk78 commented Feb 23, 2017 • edited

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

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

What did you do?

What did you expect to see?

What did you see instead?

tzneal commented Apr 11, 2017

gopherbot commented Apr 11, 2017

vimalk78 commented Apr 11, 2017

vimalk78 commented Feb 23, 2017 •

edited

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

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