go: cmd/link: segfault with statically linked binaries on linux

Discovered with @tschottdorf.

package main

import (
    "net"
    "os/user"

    "C"
)

func main() {
    for i := 0; i < 1000; i++ {
        _, _ = net.Dial("tcp", "localhost:1337")
        _, _ = user.Current()
    }
}

Note the “C” import is required, otherwise the go tool does not build a real static binary.

$ go run -ldflags '-extldflags "-static"' main.go
fatal error: unexpected signal during runtime execution
[signal 0xb code=0x1 addr=0xe5 pc=0x7fec267f8a5c]

runtime stack:
runtime.throw(0x660380, 0x2a)
    /usr/local/go/src/runtime/panic.go:527 +0x90
runtime.sigpanic()
    /usr/local/go/src/runtime/sigpanic_unix.go:12 +0x5a

goroutine 1 [syscall, locked to thread]:
runtime.cgocall(0x402620, 0xc82004bd30, 0xc800000000)
    /usr/local/go/src/runtime/cgocall.go:120 +0x11b fp=0xc82004bce0 sp=0xc82004bcb0
os/user._Cfunc_mygetpwuid_r(0x0, 0xc8200172c0, 0x7fec180008c0, 0x400, 0xc82002a0b0, 0x0)
    ??:0 +0x39 fp=0xc82004bd30 sp=0xc82004bce0
os/user.lookupUnix(0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
    /usr/local/go/src/os/user/lookup_unix.go:99 +0x723 fp=0xc82004bea0 sp=0xc82004bd30
os/user.current(0x0, 0x0, 0x0)
    /usr/local/go/src/os/user/lookup_unix.go:39 +0x42 fp=0xc82004bee0 sp=0xc82004bea0
os/user.Current(0x62eba8, 0x0, 0x0)
    /usr/local/go/src/os/user/lookup.go:9 +0x24 fp=0xc82004bf00 sp=0xc82004bee0
main.main()
    /go/src/github.com/cockroachdb/cgo_static_boom/main.go:13 +0x55 fp=0xc82004bf50 sp=0xc82004bf00
runtime.main()
    /usr/local/go/src/runtime/proc.go:111 +0x2b0 fp=0xc82004bfa0 sp=0xc82004bf50
runtime.goexit()
    /usr/local/go/src/runtime/asm_amd64.s:1696 +0x1 fp=0xc82004bfa8 sp=0xc82004bfa0

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /usr/local/go/src/runtime/asm_amd64.s:1696 +0x1
exit status 2

This was discovered in a docker image based on golang:1.5.1, but also tested against go1.5.2 and 606d9a7e (tip at the time of writing), both built from source in the container. The segfault reproduces in all three. The docker image was running in a virtualbox VM.

Output of go env:

$ go env
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"
GO15VENDOREXPERIMENT=""
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"