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vkjon opened this issue Aug 17, 2023 · 7 comments
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encoding/gob: panic decoding into local type, received remote type #62117

vkjon opened this issue Aug 17, 2023 · 7 comments
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@panjf2000
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.22

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@vkjon
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vkjon commented Aug 17, 2023

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

$ go version
go version go1.21.0 linux/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='/home/vscode/.cache/go-build'
GOENV='/home/vscode/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/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='go1.21.0'
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-build318203347=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Decode downstream gob into a local type.

What did you expect to see?

gob: decoding into local type *[]*struct {}, received remote type

What did you see instead?

panic: runtime error: index out of range [64] with length 64 [recovered]
	panic: runtime error: index out of range [64] with length 64 [recovered]
	panic: runtime error: index out of range [64] with length 64

goroutine 1 [running]:
encoding/gob.catchError(0xc000108070)
	/usr/local/go-faketime/src/encoding/gob/error.go:38 +0x6d
panic({0x4b5c20?, 0xc00001a030?})
	/usr/local/go-faketime/src/runtime/panic.go:914 +0x21f
encoding/gob.catchError(0xc0001198c8)
	/usr/local/go-faketime/src/encoding/gob/error.go:38 +0x6d
panic({0x4b5c20?, 0xc00001a030?})
	/usr/local/go-faketime/src/runtime/panic.go:914 +0x21f
encoding/gob.(*Decoder).typeString(0xc000108000?, 0x4e4480?)
	/usr/local/go-faketime/src/encoding/gob/decode.go:1085 +0x1e9
encoding/gob.(*Decoder).compileSingle(0x1800000700?, 0x40, 0xc00001cdc0)
	/usr/local/go-faketime/src/encoding/gob/decode.go:1100 +0x365
encoding/gob.(*Decoder).compileDec(0xc000108000, 0x40, 0xc00001cdc0)
	/usr/local/go-faketime/src/encoding/gob/decode.go:1132 +0x257
encoding/gob.(*Decoder).getDecEnginePtr(0xc000108000, 0x4a48a0?, 0xc00001cdc0)
	/usr/local/go-faketime/src/encoding/gob/decode.go:1189 +0x12a
encoding/gob.(*Decoder).decodeValue(0xc000108000, 0x446e00?, {0x4a48a0?, 0xc000010258?, 0xc000016601?})
	/usr/local/go-faketime/src/encoding/gob/decode.go:1234 +0xfd
encoding/gob.(*Decoder).DecodeValue(0xc000108000, {0x4a48a0?, 0xc000010258?, 0x0?})
	/usr/local/go-faketime/src/encoding/gob/decoder.go:229 +0x196
encoding/gob.(*Decoder).Decode(0xc000108000, {0x4a48a0?, 0xc000010258?})
	/usr/local/go-faketime/src/encoding/gob/decoder.go:204 +0x125
main.main()
	/tmp/sandbox717720055/prog.go:14 +0xbb
@dmitshur dmitshur added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Aug 17, 2023
@dmitshur dmitshur added this to the Backlog milestone Aug 17, 2023
@dmitshur
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Thanks for reporting.

If I understand correctly, this only happens with Go 1.21.0 but not in Go 1.20 and older, right?

CC @robpike.

@vkjon
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vkjon commented Aug 17, 2023

I didn't think to test with an older versions. You are correct, go1.20 does not panic.

@dmitshur
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Also CC @mvdan.

@gopherbot
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Change https://go.dev/cl/520757 mentions this issue: encoding/gob: prevent panic from index out of range in Decoder.typeString

@panjf2000 panjf2000 self-assigned this Aug 18, 2023
@panjf2000 panjf2000 added the NeedsFix The path to resolution is known, but the work has not been done. label Aug 18, 2023
@gopherbot gopherbot removed the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Aug 18, 2023
@dmitshur dmitshur modified the milestones: Backlog, Go1.22 Aug 18, 2023
@panjf2000
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@gopherbot please consider this for backport to 1.21, this issue may have a wide impact.

@gopherbot
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Backport issue(s) opened: #62154 (for 1.21).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

@gopherbot gopherbot mentioned this issue Aug 19, 2023
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@gopherbot
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Change https://go.dev/cl/521156 mentions this issue: [release-branch.go1.21] encoding/gob: prevent panic from index out of range in Decoder.typeString

cellularmitosis pushed a commit to cellularmitosis/go that referenced this issue Aug 24, 2023
@panjf2000 @cellularmitosis
encoding/gob: prevent panic from index out of range in Decoder.typeSt…
3b6ed3c 
…ring

I believe this bug is introduced by CL 460543 which optimizes the allocations
by changing the type of `idToType` from map to slice, but didn't update the
access code in `Decoder.typeString` that is safe for map but not for slice.

Fixes golang#62117

Change-Id: I0f2e4cc2f34c54dada1f83458ba512a6fde6dcbe
Reviewed-on: https://go-review.googlesource.com/c/go/+/520757
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
gopherbot pushed a commit that referenced this issue Aug 25, 2023
@panjf2000 @gopherbot
[release-branch.go1.21] encoding/gob: prevent panic from index out of…
745b81b 
… range in Decoder.typeString

I believe this bug is introduced by CL 460543 which optimizes the allocations
by changing the type of `idToType` from map to slice, but didn't update the
access code in `Decoder.typeString` that is safe for map but not for slice.

For #62117
Fixes #62154

Change-Id: I0f2e4cc2f34c54dada1f83458ba512a6fde6dcbe
Reviewed-on: https://go-review.googlesource.com/c/go/+/520757
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
(cherry picked from commit ba626ac)
Reviewed-on: https://go-review.googlesource.com/c/go/+/521156
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
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