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container/ring: Move not optimized for overlong moves #52524

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catenacyber opened this issue Apr 24, 2022 · 4 comments
Closed

container/ring: Move not optimized for overlong moves #52524

catenacyber opened this issue Apr 24, 2022 · 4 comments
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FrozenDueToAge help wanted NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.
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@catenacyber
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What version of Go are you using (go version)?

$ go version
go version go1.17.6 darwin/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="/Users/catena/Library/Caches/go-build"
GOENV="/Users/catena/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/catena/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/catena/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.17.6"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/catena/go/src/github.com/catenacyber/go/src/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 -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/pp/dc1dtf9x2js3v0jx_m010nqr0000gn/T/go-build4237848497=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.17.6 darwin/amd64
GOROOT/bin/go tool compile -V: compile version go1.17.6
uname -v: Darwin Kernel Version 21.3.0: Wed Jan  5 21:37:58 PST 2022; root:xnu-8019.80.24~20/RELEASE_X86_64
ProductName:	macOS
ProductVersion:	12.2.1
BuildVersion:	21D62
lldb --version: lldb-1316.0.9.41
Apple Swift version 5.6 (swiftlang-5.6.0.323.62 clang-1316.0.20.8)
gdb --version: GNU gdb (GDB) 9.1

What did you do?

Run https://go.dev/play/p/nkBS_zb1KN1

What did you expect to see?

The program finishing and printing somme dummy data

What did you see instead?

timeout running program
lol

Program exited.

Found by https://github.com/catenacyber/ngolo-fuzzing on oss-fuzz
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=46329

Doc explicitely states Move moves n % r.Len() but there is no computation od this modulo
@griesemer
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Note that the doc is correct - it does move r by n % r.Len(); the implementation is just not optimized for that case as it seems unimportant.

Feel free to fix with a corresponding test. Note this is not entirely trivial if one wants to avoid the cost of the overhead of computing the length of the ring first before making a small move, say by 1.

@griesemer griesemer added this to the Backlog milestone Apr 26, 2022
@catenacyber
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Note that the doc is correct - it does move r by n % r.Len(); the implementation is just not optimized for that case as it seems unimportant.

Indeed, I agree that the doc is correct

Feel free to fix with a corresponding test. Note this is not entirely trivial if one wants to avoid the cost of the overhead of computing the length of the ring first before making a small move, say by 1.

Is it worth it ?
I guess I can make a patch without much performance impact by checking if we wrap around, so we will at most move 2*r.Len() - 1 elements...

@griesemer griesemer changed the title container/ring: timeout in Move container/ring: Move not optimized for overlong moves Apr 27, 2022
@griesemer
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I don't think it's worth it, but you reported the issue.

@cagedmantis cagedmantis added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Apr 27, 2022
@catenacyber
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I don't think it's worth it, but you reported the issue.

Yes, I wanted to get your feedback.
So, closing this, thanks

@golang golang locked and limited conversation to collaborators Apr 27, 2023
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