x/tools/cmd/ssadump: interpreting causes a crash #43163

aykevl · 2020-12-13T19:36:53Z

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

$ go version
go version go1.15.5 linux/amd64

I've tested both Go 1.15.5 and Go 1.14.

Does this issue reproduce with the latest release?

Yes, in the latest major release and with x/tools commit d93e913.

What operating system and processor architecture are you using (`go env`)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ayke/.cache/go-build"
GOENV="/home/ayke/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/ayke/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/ayke:/home/ayke"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build217519519=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I have the following code in a directory named const:

package main

import _ "runtime"

func main() {
	println("test")
}

I run it with ssadump -run . when I'm in that directory (or alternatively ssadump -interp=RT -run .).

What did you expect to see?

I expect it to print "test".

What did you see instead?

It crashes:

$ ssadump -run .
Running: _/home/ayke/tmp/const
panic: runtime error: invalid memory address or nil pointer dereference

$ ssadump -interp=RT -run .
Running: _/home/ayke/tmp/const
Entering _/home/ayke/tmp/const.init.
.0:
	 t0 = *init$guard
	 if t0 goto 2 else 1
.1:
	 *init$guard = true:bool
	 t1 = runtime.init()
Entering runtime.init.
[... removed excessive log messages...]
Entering runtime.float64frombits at /usr/local/go/src/runtime/float.go:51:6.
.0:
	 t0 = new uint64 (b)
	 *t0 = b
	 t1 = convert unsafe.Pointer <- *uint64 (t0)
	 t2 = convert *float64 <- unsafe.Pointer (t1)
	 t3 = *t2
Leaving runtime.float64frombits, resuming runtime.init at /usr/local/go/src/runtime/float.go:9:26.
Leaving runtime.init, resuming _/home/ayke/tmp/const.init.
Leaving _/home/ayke/tmp/const.init.
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x689fa6]

goroutine 1 [running]:
golang.org/x/tools/go/ssa/interp.load(0x767420, 0x8cf9c0, 0x0, 0x400000c000487040, 0x3)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/value.go:338 +0x1a6
golang.org/x/tools/go/ssa/interp.unop(0xc0036288a0, 0x6a6860, 0x0, 0x6a6860, 0x0)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/ops.go:847 +0x739
golang.org/x/tools/go/ssa/interp.visitInstr(0xc004d43500, 0x76dd00, 0xc0036288a0, 0x4)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:195 +0x745
golang.org/x/tools/go/ssa/interp.runFrame(0xc004d43500)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:579 +0xdc
golang.org/x/tools/go/ssa/interp.callSSA(0xc004d219d0, 0xc004d42f00, 0x18600a, 0xc0005a92c0, 0xc004e754c0, 0x1, 0x1, 0x0, 0x0, 0x0, ...)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:524 +0x5da
golang.org/x/tools/go/ssa/interp.call(0xc004d219d0, 0xc004d42f00, 0x18600a, 0x7053c0, 0xc0005a92c0, 0xc004e754c0, 0x1, 0x1, 0x0, 0x80)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:462 +0xd5
golang.org/x/tools/go/ssa/interp.visitInstr(0xc004d42f00, 0x76c740, 0xc000a2ac80, 0x4)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:202 +0x886
golang.org/x/tools/go/ssa/interp.runFrame(0xc004d42f00)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:579 +0xdc
golang.org/x/tools/go/ssa/interp.callSSA(0xc004d219d0, 0xc004d42e80, 0x0, 0xc0015fbb80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:524 +0x5da
golang.org/x/tools/go/ssa/interp.call(0xc004d219d0, 0xc004d42e80, 0x0, 0x7053c0, 0xc0015fbb80, 0x0, 0x0, 0x0, 0x18, 0x80)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:462 +0xd5
golang.org/x/tools/go/ssa/interp.visitInstr(0xc004d42e80, 0x76c740, 0xc001265080, 0x4)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:202 +0x886
golang.org/x/tools/go/ssa/interp.runFrame(0xc004d42e80)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:579 +0xdc
golang.org/x/tools/go/ssa/interp.callSSA(0xc004d219d0, 0x0, 0x0, 0xc00153e500, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:524 +0x5da
golang.org/x/tools/go/ssa/interp.call(0xc004d219d0, 0x0, 0x0, 0x7053c0, 0xc00153e500, 0x0, 0x0, 0x0, 0xc000605bf8, 0x1f)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:462 +0xd5
golang.org/x/tools/go/ssa/interp.Interpret(0xc001cbd620, 0x3, 0x76ad20, 0xc00018c080, 0xc0000cbdc0, 0x15, 0x0, 0x0, 0x0, 0x2)
	/home/ayke/src/golang.org/x/tools/go/ssa/interp/interp.go:701 +0x5ec
main.doMain(0x0, 0x0)
	/home/ayke/src/golang.org/x/tools/cmd/ssadump/main.go:170 +0x78c
main.main()
	/home/ayke/src/golang.org/x/tools/cmd/ssadump/main.go:64 +0x26

What I really wanted to report was what appears to be a bug in either go/constant or x/tools/go/ssa, but I'm not sure how to reproduce this in an easy way with ssadump crashing on any program that I feed it.

The text was updated successfully, but these errors were encountered:

toothrot · 2020-12-17T18:43:38Z

/cc @golang/tools-team

timothy-king · 2022-09-16T23:34:07Z

"runtime" is required by ssadump to interpret.

		if prog.ImportedPackage("runtime") == nil {
			return fmt.Errorf("-run: program does not depend on runtime")
		}

However, x/tools/go/ssa/interp can no longer handle runtime's use of unsafe.Pointer during package initialization.

	uint32Type *_type = efaceOf(&uint32Eface)._type

gopherbot · 2022-10-10T20:54:45Z

Change https://go.dev/cl/441817 mentions this issue: cmd/ssadump: disable run mode with runtime package

Changes `ssadump -run` to ensure that the package runtime is not imported (changed from must be imported). For several years, the runtime package has used unsafe constructs x/tools/go/ssa/interp cannot interpret. This must have been failing a similar amount of time. This is unfortunate, but is unlikely to be addressed soon. For golang/go#43163 Change-Id: I9e2aee640ff7b1123e591e6c49cac9967c5e8da8 Reviewed-on: https://go-review.googlesource.com/c/tools/+/441817 Run-TryBot: Tim King <[email protected]> gopls-CI: kokoro <[email protected]> Reviewed-by: Alan Donovan <[email protected]> TryBot-Result: Gopher Robot <[email protected]>

timothy-king · 2022-10-11T20:44:25Z

interp is only really needed for testing and a redesign to stub out "runtime" or fixing the memory model to unsafe.Pointer dereferences after type switches is quite a bit of work. We have decided to address this by giving a better error message in ssadump and not panicing. So it will continue to be the case that only trivial programs can be interpreted by ssadump.

Closing for now as unfortunate.

gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Dec 13, 2020

gopherbot added this to the Unreleased milestone Dec 13, 2020

aykevl mentioned this issue Dec 13, 2020

go/constant: cannot deal with exponential notation #43165

Closed

toothrot added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Dec 17, 2020

timothy-king self-assigned this Sep 16, 2022

timothy-king added Unfortunate and removed NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Oct 11, 2022

timothy-king closed this as completed Oct 11, 2022

golang locked and limited conversation to collaborators Oct 11, 2023

gopherbot added the FrozenDueToAge label Oct 11, 2023

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x/tools/cmd/ssadump: interpreting causes a crash #43163

x/tools/cmd/ssadump: interpreting causes a crash #43163

aykevl commented Dec 13, 2020

toothrot commented Dec 17, 2020

timothy-king commented Sep 16, 2022

gopherbot commented Oct 10, 2022

timothy-king commented Oct 11, 2022

x/tools/cmd/ssadump: interpreting causes a crash #43163

x/tools/cmd/ssadump: interpreting causes a crash #43163

Comments

aykevl commented Dec 13, 2020

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

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

What did you do?

What did you expect to see?

What did you see instead?

toothrot commented Dec 17, 2020

timothy-king commented Sep 16, 2022

gopherbot commented Oct 10, 2022

timothy-king commented Oct 11, 2022

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

What operating system and processor architecture are you using (`go env`)?