net/http: panic in HTTP ResponseWriter

[thierry-f-78]

Go version

1.22.7 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/cache/go-build'
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/cache/go-mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/root/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.22.7'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build959956862=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I Use http handler to process homemade timeouts.

What did you see happen?

Description

A panic occurs in an http.ResponseWriter under specific conditions. The issue is inconsistent and difficult to reproduce reliably. It has been observed frequently on a colleague's PC and occasionally on other machines.

Reproducibility

• Cannot be reproduced consistently
• Never encountered on macOS ARM with the program compiled for ARM

Error Message

runtime error: invalid memory address or nil pointer dereference

Stack Trace

2024-10-01 15:59:30 goroutine 15523 [running]:
2024-10-01 15:59:30 runtime/debug.Stack()
2024-10-01 15:59:30     runtime/debug/stack.go:24 +0x5e
2024-10-01 15:59:30 server/pkg/sentry.Recover()
2024-10-01 15:59:30     server/pkg/sentry/sentry.go:50 +0x30a
2024-10-01 15:59:30 panic({0x1ecc0e0?, 0x39c4550?})
2024-10-01 15:59:30     runtime/panic.go:770 +0x132
2024-10-01 15:59:30 bufio.(*Writer).Write(0xc000fae000, {0xc000116000?, 0x456d8c?, 0xc00bf13fa0?})
2024-10-01 15:59:30     bufio/bufio.go:679 +0xe1
2024-10-01 15:59:30 net/http.(*response).write(0xc004e4cc40, 0x6340, {0xc000116000, 0x6340, 0x8000}, {0x0, 0x0})
2024-10-01 15:59:30     net/http/server.go:1658 +0x2fe
2024-10-01 15:59:30 net/http.(*response).Write(0x0?, {0xc000116000?, 0xc00c8e2601?, 0x1000000000001?})
2024-10-01 15:59:30     net/http/server.go:1616 +0x2a
2024-10-01 15:59:30 server/pkg/api/server.(*writeTimeoutHandler).Write.func1({0x29dcc50?, 0xc004e4cc40?})
2024-10-01 15:59:30     server/pkg/api/server/server.go:125 +0x8c
2024-10-01 15:59:30 created by server/pkg/api/server.(*writeTimeoutHandler).Write in goroutine 15134
2024-10-01 15:59:30     server/pkg/api/server/server.go:122 +0x1b2

What did you expect to see?

Maybe an error, or nothing, but not a panic.

[gabyhelp]

Related Issues and Documentation

• net/http: ResponseController panic #58237 (closed)
• net/http: panic caused by nil dereference looking up route #64839 (closed)
• net/http: pc close panics #60862 (closed)
• http.TimeoutHandler breaks with GOMAXPROCS n > 1 #8414 (closed)
• x/net/http2: closeStream has panic #59601 (closed)
• net/http: http.TimeoutHandler rewrites panic stack trace #51587
• net/http: on panic http.server re-runs the handler multiple times on Windows #57588 (closed)
• Uncomplete strange panic message #47138 (closed)
• net/http: client.Do(request) panics in time.stopTimer #38219 (closed)
• x/net/http2/h2c panic #67168 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[seankhliao]

It looks more likely to be a problem with your code. I don't think this is actionable without a reproducer