go (original) (raw)

Go version

1.23 (all)

Output of `go env` in your module/workspace:

set GO111MODULE= set GOARCH=amd64 set GOBIN= set GOCACHE=C:\Users...\AppData\Local\go-build set GOENV=C:\Users...\AppData\Roaming\go\env set GOEXE=.exe set GOEXPERIMENT= set GOFLAGS= set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOINSECURE= set GOMODCACHE=C:\Users\calvip\go\pkg\mod set GONOPROXY= set GONOSUMDB= set GOOS=windows set GOPATH=C:\Users...\go set GOPRIVATE= set GOPROXY=https://proxy.golang.org,direct set GOROOT=c:\go set GOSUMDB=sum.golang.org set GOTMPDIR= set GOTOOLDIR=c:\go\pkg\tool\windows_amd64 set GOVCS= set GOVERSION=go1.22.3 set GCCGO=gccgo set GOAMD64=v1 set AR=ar set CC=gcc set CXX=g++ set CGO_ENABLED=1 set GOMOD=NUL set GOWORK= set CGO_CFLAGS=-O2 -g set CGO_CPPFLAGS= set CGO_CXXFLAGS=-O2 -g set CGO_FFLAGS=-O2 -g set CGO_LDFLAGS=-O2 -g set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=C:\Users.....\AppData\Local\Temp\go-build939558769=/tmp/go-build -gno-record-gcc-switches

What did you do?

Static analysis of the x/crypto/sha3/shake.go function

What did you see happen?

The code

func bytepad(input []byte, w int) []byte { // leftEncode always returns max 9 bytes buf := make([]byte, 0, 9+len(input)+w) buf = append(buf, leftEncode(uint64(w))...) buf = append(buf, input...) padlen := w - (len(buf) % w) return append(buf, make([]byte, padlen)...) }

and in particular

padlen := w - (len(buf) % w)

is not working properly when len(buf) % w == 0, causing an undesired padding.

The function appear to work only if the length of the input + length of the letfencoding is not a multiple of w already.

What did you expect to see?