cmd/link: linker produces invalid binaries on FreeBSD when cgo is used and linkflag -X passed twice #23273
Description
tl;dr: generated binary segfaults on init if both 1) uses cgo and 2) -X is passed twice in -ldflags
- What version of Go are you using (
go version)?
go version go1.9.2 freebsd/amd64
- Does this issue reproduce with the latest release?
yes
- What operating system and processor architecture are you using (
go env)?
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="freebsd"
GOOS="freebsd"
GOPATH="/data/home/kena/src/go"
GORACE=""
GOROOT="/data/home/kena/src/go1.9.2"
GOTOOLDIR="/data/home/kena/src/go1.9.2/pkg/tool/freebsd_amd64"
GCCGO="gccgo"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build623559632=/tmp/go-build -gno-record-gcc-switches"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
- What did you do?
Using the following file test.go:
package main
import "fmt"
// #include <stdio.h>
// int x = 42;
import "C"
var test string
func init() {
fmt.Println(test, C.x)
}
func main() {
fmt.Println("world")
}I ran:
go build -x -ldflags='-X main.test=hello -X main.test=hello'
./test
- What did you expect to see?
hello 42
world
- What did you see instead?
unexpected fault address 0x98b270
fatal error: fault
[signal SIGSEGV: segmentation violation code=0x1 addr=0x98b270 pc=0x450982]
goroutine 1 [running, locked to thread]:
runtime.throw(0x4b4dae, 0x5)
/data/home/kena/src/go1.9.2/src/runtime/panic.go:605 +0x95 fp=0xc42005bbf8 sp=0xc42005bbd8 pc=0x426c95
runtime.sigpanic()
/data/home/kena/src/go1.9.2/src/runtime/signal_unix.go:374 +0x227 fp=0xc42005bc48 sp=0xc42005bbf8 pc=0x439b97
runtime.memmove(0xc42008c038, 0x98b270, 0x5)
/data/home/kena/src/go1.9.2/src/runtime/memmove_amd64.s:161 +0x122 fp=0xc42005bc50 sp=0xc42005bc48 pc=0x450982
fmt.(*buffer).WriteString(...)
/data/home/kena/src/go1.9.2/src/fmt/print.go:82
fmt.(*fmt).padString(0xc4200b0040, 0x98b270, 0x5)
/data/home/kena/src/go1.9.2/src/fmt/format.go:110 +0x9c fp=0xc42005bcd8 sp=0xc42005bc50 pc=0x47ce2c
fmt.(*fmt).fmt_s(0xc4200b0040, 0x98b270, 0x5)
/data/home/kena/src/go1.9.2/src/fmt/format.go:328 +0x61 fp=0xc42005bd10 sp=0xc42005bcd8 pc=0x47dbd1
fmt.(*pp).fmtString(0xc4200b0000, 0x98b270, 0x5, 0x76)
/data/home/kena/src/go1.9.2/src/fmt/print.go:430 +0x11f fp=0xc42005bd48 sp=0xc42005bd10 pc=0x480d6f
fmt.(*pp).printArg(0xc4200b0000, 0x4965e0, 0xc4200841b0, 0x76)
/data/home/kena/src/go1.9.2/src/fmt/print.go:664 +0x7b5 fp=0xc42005bdc8 sp=0xc42005bd48 pc=0x4830c5
fmt.(*pp).doPrintln(0xc4200b0000, 0xc42005bf40, 0x2, 0x2)
/data/home/kena/src/go1.9.2/src/fmt/print.go:1136 +0x56 fp=0xc42005be58 sp=0xc42005bdc8 pc=0x486166
fmt.Fprintln(0x71c800, 0xc420094008, 0xc42005bf40, 0x2, 0x2, 0x4960a0, 0xc420084100, 0xc42008c030)
/data/home/kena/src/go1.9.2/src/fmt/print.go:247 +0x58 fp=0xc42005bec0 sp=0xc42005be58 pc=0x47f568
fmt.Println(0xc42005bf40, 0x2, 0x2, 0xc42008c030, 0xc42005bf60, 0x486478)
/data/home/kena/src/go1.9.2/src/fmt/print.go:257 +0x57 fp=0xc42005bf10 sp=0xc42005bec0 pc=0x47f667
main.init.0()
/data/home/kena/src/go/src/github.com/cockroachdb/cockroach/t/test.go:12 +0xc7 fp=0xc42005bf70 sp=0xc42005bf10 pc=0x4866e7
main.init()
<autogenerated>:1 +0x4e fp=0xc42005bf80 sp=0xc42005bf70 pc=0x4867ce
runtime.main()
/data/home/kena/src/go1.9.2/src/runtime/proc.go:173 +0x1c5 fp=0xc42005bfe0 sp=0xc42005bf80 pc=0x428325
runtime.goexit()
/data/home/kena/src/go1.9.2/src/runtime/asm_amd64.s:2337 +0x1 fp=0xc42005bfe8 sp=0xc42005bfe0 pc=0x4500b1
If I either remove the cgo usage in test.go or remove the duplicate -X flag in the link flags, the problem goes away and the program runs successfully.