unicode/utf8: invalid memory address or nil pointer dereference

[yaa110]

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

$ go version
go version go1.17.5 linux/amd64

Does this issue reproduce with the latest release?

yes

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/yaa110/.cache/go-build"
GOENV="/home/yaa110/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/yaa110/go/pkg/mod"
GONOPROXY="git.cafebazaar.ir"
GONOSUMDB="git.cafebazaar.ir"
GOOS="linux"
GOPATH="/home/yaa110/go"
GOPRIVATE="git.cafebazaar.ir"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.17.5"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/yaa110/Projects/cdn-exporter/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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3135926648=/tmp/go-build -gno-record-gcc-switches"

What did you do?

It happens periodically when a long-running service is run.

What did you expect to see?

No panic due to segfault

What did you see instead?

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x4f483e]
goroutine 219 [running]:
unicode/utf8.ValidString({0x0, 0xc001d9de78})
	/usr/local/go/src/unicode/utf8/utf8.go:514 +0x5e
github.com/prometheus/client_golang/prometheus.validateLabelValues({0xc002a980f0, 0x5, 0x55}, 0x9)
	/app/vendor/github.com/prometheus/client_golang/prometheus/labels.go:77 +0x185
github.com/prometheus/client_golang/prometheus.(*MetricVec).hashLabelValues(0xc0003c2150, {0xc002a980f0, 0xc001d9df20, 0x476eb4})
	/app/vendor/github.com/prometheus/client_golang/prometheus/vec.go:226 +0x47
github.com/prometheus/client_golang/prometheus.(*MetricVec).GetMetricWithLabelValues(0xc0003c2150, {0xc002a980f0, 0x5, 0x5})
	/app/vendor/github.com/prometheus/client_golang/prometheus/vec.go:192 +0x2d
github.com/prometheus/client_golang/prometheus.(*CounterVec).GetMetricWithLabelValues(...)
	/app/vendor/github.com/prometheus/client_golang/prometheus/counter.go:214
github.com/prometheus/client_golang/prometheus.(*CounterVec).WithLabelValues(0xc88080, {0xc002a980f0, 0x8, 0x1})
	/app/vendor/github.com/prometheus/client_golang/prometheus/counter.go:246 +0x25

[mvdan]

This sounds like some sort of memory corruption or data race, or perhaps some use of unsafe.

I would suggest you to ask in the forums first; see https://golang.org/wiki/Questions. This issue as-is doesn't point to a bug in Go itself, and there is no way to reproduce the crash or further investigate it.

[yaa110]

@mvdan I checked the code again and it is due to a race condition with high probability. Thanks