GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/go"
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-build694367367=/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"

$ docker run --rm -it golang:1.8-alpine sh
# apk add -U build-base
# cat > sum.go
// sum.go
package main

import "C"

//export sum
func sum(x, y int) int {
    return x + y
}

func main() {}
^C
# cat > sum.c
#include <stdio.h>
#include "sum.h"

int main(void) {

    int z = sum(1, 2);
    printf("1+2=%d\n", z);

    return 0;
}
^C
# go build -buildmode=c-shared -o sum.so
# gcc sum.c ./sum.so -o sum && ./sum
Segmentation fault

# apk add -U gdb
# ulimit -c unlimited
# gcc sum.c ./sum.so -o sum && ./sum
# gdb ./sum core
(gdb) bt
#0  runtime.raise () at /usr/local/go/src/runtime/sys_linux_amd64.s:110
#1  0x00007fadef86cddb in runtime.dieFromSignal (sig=11) at /usr/local/go/src/runtime/signal_unix.go:323
#2  0x00007fadef86d2a1 in runtime.sigfwdgo (sig=11, info=0x7fadefd88130, ctx=0x7fadefd88000, ~r3=false) at /usr/local/go/src/runtime/signal_unix.go:501
#3  0x00007fadef86c70b in runtime.sigtrampgo (sig=11, info=0x7fadefd88130, ctx=0x7fadefd88000) at /usr/local/go/src/runtime/signal_unix.go:200
#4  0x00007fadef883133 in runtime.sigtramp () at /usr/local/go/src/runtime/sys_linux_amd64.s:262
#5  <signal handler called>
#6  0x00007fadef85a02c in runtime.sysargs (argc=-273804016, argv=0x0) at /usr/local/go/src/runtime/os_linux.go:199
#7  0x00007fadef86962c in runtime.args (c=-273804016, v=0x0) at /usr/local/go/src/runtime/runtime1.go:64
#8  0x00007fadef87f60b in runtime.rt0_go () at /usr/local/go/src/runtime/asm_amd64.s:156
#9  0x00000000efae1510 in ?? ()
#10 0x0000000000000000 in ?? ()