panic on fasthttphandler

[JayChoi1736]

i've got these panic error log.

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0xf6a2bc]

goroutine 108517 [running]:
github.com/valyala/fasthttp.(*firstByteReader).Read(0xc0291b5908?, {0xc02a341fee?, 0x7f88c5c159a8?, 0x200?})
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:834 +0x5c
bufio.(*Reader).Read(0xc04327a120, {0xc02a341fee, 0x1bd9, 0x1e386b0?})
	/usr/local/src/bufio/bufio.go:222 +0x106
github.com/valyala/fasthttp.(*requestStream).Read(0xc04d60c9c0, {0xc02a341fee?, 0xc0291b57b8?, 0x1e386b0?})
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/streaming.go:75 +0x2e5
github.com/valyala/bytebufferpool.(*ByteBuffer).ReadFrom(0xc0299d9140, {0x1e2eae0, 0xc04d60c9c0})
	/go/pkg/mod/github.com/valyala/bytebufferpool@v1.0.0/bytebuffer.go:45 +0x13e
io.copyBuffer({0x1e2e920, 0xc0299d9140}, {0x1e2eae0, 0xc04d60c9c0}, {0xc0293ca000, 0x1000, 0x1000})
	/usr/local/src/io/io.go:412 +0x14b
io.CopyBuffer({0x1e2e920?, 0xc0299d9140?}, {0x1e2eae0?, 0xc04d60c9c0?}, {0xc0293ca000?, 0xc0430019f0?, 0x2?})
	/usr/local/src/io/io.go:399 +0x3c
github.com/valyala/fasthttp.copyZeroAlloc({0x1e2e920, 0xc0299d9140}, {0x1e2eae0, 0xc04d60c9c0})
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:1981 +0x7e
github.com/valyala/fasthttp.(*Request).bodyBytes(0xc03bb0d600)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:371 +0xec
github.com/valyala/fasthttp.(*Request).Body(0x20?)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:671 +0x9e
github.com/valyala/fasthttp.(*RequestCtx).PostBody(...)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:1415
github.com/valyala/fasthttp/fasthttpadaptor.ConvertRequest(0xc03bb0d600, 0xc04e9c6ea0, 0x1)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/fasthttpadaptor/request.go:15 +0x37
github.com/valyala/fasthttp/fasthttpadaptor.NewFastHTTPHandler.func1(0xc03bb0d600)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/fasthttpadaptor/adaptor.go:50 +0x85
github.com/valyala/fasthttp.TimeoutWithCodeHandler.func1.1()
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:471 +0x33
created by github.com/valyala/fasthttp.TimeoutWithCodeHandler.func1

panic: runtime error: slice bounds out of range [:4167] with capacity 4096

goroutine 635068 [running]:
bufio.(*Reader).Read(0xc05aa93500, {0xc05b795ff7?, 0x9?, 0x4000?})
	/usr/local/src/bufio/bufio.go:249 +0x2ed
github.com/valyala/fasthttp.(*requestStream).Read(0xc04f278ff0, {0xc05b795ff7?, 0xc0669719d0?, 0xc05b77a000?})
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/streaming.go:75 +0x2e5
github.com/valyala/bytebufferpool.(*ByteBuffer).ReadFrom(0xc041d8bdd0, {0x1e2eae0, 0xc04f278ff0})
	/go/pkg/mod/github.com/valyala/bytebufferpool@v1.0.0/bytebuffer.go:45 +0x13e
io.copyBuffer({0x1e2e920, 0xc041d8bdd0}, {0x1e2eae0, 0xc04f278ff0}, {0xc01c746000, 0x1000, 0x1000})
	/usr/local/src/io/io.go:412 +0x14b
io.CopyBuffer({0x1e2e920?, 0xc041d8bdd0?}, {0x1e2eae0?, 0xc04f278ff0?}, {0xc01c746000?, 0x0?, 0xc0321a7b00?})
	/usr/local/src/io/io.go:399 +0x3c
github.com/valyala/fasthttp.copyZeroAlloc({0x1e2e920, 0xc041d8bdd0}, {0x1e2eae0, 0xc04f278ff0})
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:1981 +0x7e
github.com/valyala/fasthttp.(*Request).bodyBytes(0xc033e59b80)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:371 +0xec
github.com/valyala/fasthttp.(*Request).Body(0x3?)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/http.go:671 +0x9e
github.com/valyala/fasthttp.(*RequestCtx).PostBody(...)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:1415
github.com/valyala/fasthttp/fasthttpadaptor.ConvertRequest(0xc033e59b80, 0xc066971ea0, 0x1)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/fasthttpadaptor/request.go:15 +0x37
github.com/valyala/fasthttp/fasthttpadaptor.NewFastHTTPHandler.func1(0xc033e59b80)
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/fasthttpadaptor/adaptor.go:50 +0x85
github.com/valyala/fasthttp.TimeoutWithCodeHandler.func1.1()
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:471 +0x33
created by github.com/valyala/fasthttp.TimeoutWithCodeHandler.func1
	/go/pkg/mod/github.com/valyala/fasthttp@v1.34.0/server.go:470 +0x16b

source code

	handler := newCorsHandler(srv, cors)
	handler = newVHostHandler(vhosts, handler)

	fhandler := fasthttpadaptor.NewFastHTTPHandler(handler)
	fhandler = fasthttp.TimeoutHandler(fhandler, timeouts.ExecutionTimeout, "timeout")

	return &fasthttp.Server{
		Concurrency:        ConcurrencyLimit,
		Handler:            fhandler,
		ReadTimeout:        timeouts.ReadTimeout,
		WriteTimeout:       timeouts.WriteTimeout,
		IdleTimeout:        timeouts.IdleTimeout,
		MaxRequestBodySize: common.MaxRequestContentLength,
		StreamRequestBody: true,
		ReduceMemoryUsage:  true,
	}

func newCorsHandler(srv http.Handler, allowedOrigins []string) http.Handler {
	// disable CORS support if user has not specified a custom CORS configuration
	if len(allowedOrigins) == 0 {
		return srv
	}
	c := cors.New(cors.Options{
		AllowedOrigins: allowedOrigins,
		AllowedMethods: []string{http.MethodPost, http.MethodGet},
		MaxAge:         600,
		AllowedHeaders: []string{"*"},
	})
	return c.Handler(srv)
}

[li-jin-gou]

Is it possible that you are using RequestCtx or any of their members after your handler has returned?

[erikdubbelboer]

I see you 👍 the comment above @JayChoi1736 , was that the issue? Can this be closed?

[JayChoi1736]

i've checked, but doesn't work.
instead of that, turning off StreamRequestBody flag works. (1.34.0)

[gaby]

I have seen something similar happen if the request is sent without a Body and the server tries to read from it. But in the example code here it doesnt seem the request is being used.

[misiek08]

Can you show newVHostHandler?
I consider you check content-length, try to read whole request, but fasthttp is streaming it to you. Your handler is not streaming the request/response flow, so you get the error and panic.