image/jpeg: "bad RST marker" error when decoding

[haoyang-zheng]

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

$ go version
go version go1.14.4 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/teikouyou/Library/Caches/go-build"
GOENV="/Users/teikouyou/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/teikouyou/dev/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.14.4/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.14.4/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/d7/wlm33f9550x_3bzzp_3b32h40000gn/T/go-build574141687=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

The following error occurred when I decoded a specific image.

invalid JPEG format: bad RST marker

Part of binary data of the image

ff ff ff ff ff ff ff ff ff ff ff ff d0 fd 32 4b

The correct marker here should be [ ff d0 ], but there is some ff bytes in front of it.

It seems that there is a consecutive 0xFF bytes in the SOS segment that causes problems in marker's matching.

This is a quote from jpeg Wikipedia.
https://en.wikipedia.org/wiki/JPEG#Syntax_and_structure

Note that consecutive 0xFF bytes are used as fill bytes for padding purposes, although this fill byte padding should only ever take place for markers immediately following entropy-coded scan data (see JPEG specification section B.1.1.2 and E.1.2 for details; specifically "In all cases where markers are appended after the compressed data, optional 0xFF fill bytes may precede the marker"

So I think this situation should be taken into account at image/jpeg/scan.go

go/src/image/jpeg/scan.go

Line 332 in 4f2a2d7

if d.tmp[0] != 0xff || d.tmp[1] != expectedRST {

What did you expect to see?

Image successfully decoded

What did you see instead?

invalid JPEG format: bad RST marker

[dmitshur]

/cc @nigeltao @robpike per owners.

[gopherbot]

Change https://golang.org/cl/260837 mentions this issue: image/jpeg: skip consecutive 0xff bytes

[moosepants]

@haoyang-zheng Do you have the example file for this issue to test against?

[gopherbot]

Change https://golang.org/cl/382754 mentions this issue: image/jpeg: improve handling of JPEG restart markers in non-ideal cases