x/debug: nil ptr dereference when parsing runtime.itabTableType

[pwschuurman]

Go version

go1.25-20250216-RC00

Output of go env in your module/workspace:

AR='ar'
CC='clang'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='clang++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/workspace/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/workspace/.config/go/env'
GOEXE=''
GOEXPERIMENT='fieldtrack,boringcrypto'
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build829528664=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/workspace/github_workspaces/debug/go.mod'
GOMODCACHE='/workspace/go/pkg/mod'
GOOS='linux'
GOPATH='/workspace/go'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/workspace/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/workspace/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/google-golang/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.25-20250216-RC00 cl/727547642 +d524e1eccd X:fieldtrack,boringcrypto'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

Ran viewcore on a coredump that had a runtime.itabTableType type allocated in heap. This caused the application to crash with a nil ptr dereference.

What did you see happen?

Core "tmp/core.283046" was generated by "/gce-pd-csi-driver"
Entering interactive mode (type 'help' for commands)
(viewcore) histogram
Error while trying to run command "histogram": runtime error: invalid memory address or nil pointer dereference
Stack: goroutine 1 [running]:
runtime/debug.Stack()
        /usr/lib/google-golang/src/runtime/debug/stack.go:26 +0x5e
main.capturePanic.func1()
        /workspace/debug/cmd/viewcore/main.go:372 +0x3d
panic({0x9e8b20?, 0xecb700?})
        /usr/lib/google-golang/src/runtime/panic.go:799 +0x132
golang.org/x/debug/internal/gocore.(*Type).field(...)
        /workspace/debug/internal/gocore/type.go:86
golang.org/x/debug/internal/gocore.runtimeItab.Type(...)
        /workspace/debug/internal/gocore/type.go:196
golang.org/x/debug/internal/gocore.(*Process).typeObject(0xc000280000, 0x300b8f0, 0xc001f242a0, {0xb348b0, 0xc000274000}, 0xc00b1e3280)
        /workspace/debug/internal/gocore/type.go:645 +0x155
golang.org/x/debug/internal/gocore.(*Process).doTypeHeap.func2(0x0?)
        /workspace/debug/internal/gocore/type.go:536 +0x91
golang.org/x/debug/internal/gocore.(*Process).ForEachRoot(...)
        /workspace/debug/internal/gocore/object.go:191
golang.org/x/debug/internal/gocore.(*Process).doTypeHeap(0xc000280000)
        /workspace/debug/internal/gocore/type.go:529 +0x1f6
sync.(*Once).doSlow(0x564562?, 0xc00b1e3560?)
        /usr/lib/google-golang/src/sync/once.go:78 +0xab
sync.(*Once).Do(...)
        /usr/lib/google-golang/src/sync/once.go:69
golang.org/x/debug/internal/gocore.(*Process).typeHeap(...)
        /workspace/debug/internal/gocore/type.go:400
golang.org/x/debug/internal/gocore.(*Process).Type(0xc000280000, 0xc000034000)
        /workspace/debug/internal/gocore/object.go:219 +0x4a
main.typeName(0xc000280000, 0xc000034000)
        /workspace/debug/cmd/viewcore/main.go:789 +0x9e
main.runHistogram.func1(0xc000280000?, 0xc000034000, 0x8?)
        /workspace/debug/cmd/viewcore/main.go:484 +0x3a
golang.org/x/debug/internal/gocore.(*Process).ForEachRootPtr.func1(0x0, 0xc00b35afc0?)
        /workspace/debug/internal/gocore/object.go:257 +0x3f
golang.org/x/debug/internal/gocore.walkRootTypePtrs(0xc000280000, 0xc002b15bc0, {0xc00b1e3718, 0x8, 0x8}, 0x0, 0xc007c4c360?, 0xc00b1e3720)
        /workspace/debug/internal/gocore/root.go:163 +0x2ab
golang.org/x/debug/internal/gocore.(*Process).forEachRootPtr(...)
        /workspace/debug/internal/gocore/object.go:269
golang.org/x/debug/internal/gocore.(*Process).ForEachRootPtr(0xc0000fa300?, 0xa6acf5?, 0x3?)
        /workspace/debug/internal/gocore/object.go:254 +0x4b
main.runHistogram(0xc0000fa300?, {0xeffd80?, 0x4?, 0xa6b4df?})
        /workspace/debug/cmd/viewcore/main.go:483 +0x1fb
github.com/spf13/cobra.(*Command).execute(0xed62e0, {0xeffd80, 0x0, 0x0})
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:944 +0x843
github.com/spf13/cobra.(*Command).ExecuteC(0xc0000ff208)
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:992
main.runRoot.func2()
        /workspace/debug/cmd/viewcore/main.go:361 +0x7c
main.capturePanic(0xb32820?)
        /workspace/debug/cmd/viewcore/main.go:376 +0x51
main.runRoot(0xed5760, {0xc00007e880?, 0x4?, 0xa6b4df?})
        /workspace/debug/cmd/viewcore/main.go:358 +0x672
github.com/spf13/cobra.(*Command).execute(0xed5760, {0xc000022120, 0x2, 0x2})
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:944 +0x843
github.com/spf13/cobra.(*Command).ExecuteC(0xed5760)
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        /gopath/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:992
main.main()
        /workspace/debug/cmd/viewcore/main.go:244 +0x132

Core "tmp/core.283046" was generated by "/gce-pd-csi-driver"
Entering interactive mode (type 'help' for commands)
(viewcore) histogram
Error while trying to run command "histogram": runtime error: invalid memory address or nil pointer dereference
Stack: goroutine 1 [running]:
runtime/debug.Stack()
        /usr/lib/google-golang/src/runtime/debug/stack.go:26 +0x5e
main.capturePanic.func1()
        /workspace/debug/cmd/viewcore/main.go:372 +0x3d
panic({0x9e8b20?, 0xecb700?})
        /usr/lib/google-golang/src/runtime/panic.go:799 +0x132
golang.org/x/debug/internal/gocore.(*Process).typeObject(0xc0002ca000, 0x300b8f0, 0xc0033a8300, {0xb348b0, 0xc0002be000}, 0xc00b28d280)
        /workspace/debug/internal/gocore/type.go:648 +0xedb
golang.org/x/debug/internal/gocore.(*Process).doTypeHeap.func2(0x0?)
        /workspace/debug/internal/gocore/type.go:539 +0x91
golang.org/x/debug/internal/gocore.(*Process).ForEachRoot(...)
        /workspace/debug/internal/gocore/object.go:191
golang.org/x/debug/internal/gocore.(*Process).doTypeHeap(0xc0002ca000)
        /workspace/debug/internal/gocore/type.go:532 +0x1f6
sync.(*Once).doSlow(0x564562?, 0xc00b28d560?)
        /usr/lib/google-golang/src/sync/once.go:78 +0xab
sync.(*Once).Do(...)
        /usr/lib/google-golang/src/sync/once.go:69
golang.org/x/debug/internal/gocore.(*Process).typeHeap(...)
        /workspace/debug/internal/gocore/type.go:403
golang.org/x/debug/internal/gocore.(*Process).Type(0xc0002ca000, 0xc000034000)
        /workspace/debug/internal/gocore/object.go:219 +0x4a
main.typeName(0xc0002ca000, 0xc000034000)
        /workspace/debug/cmd/viewcore/main.go:789 +0x9e
main.runHistogram.func1(0xc0002ca000?, 0xc000034000, 0x8?)
        /workspace/debug/cmd/viewcore/main.go:484 +0x3a
golang.org/x/debug/internal/gocore.(*Process).ForEachRootPtr.func1(0x0, 0xc00ac7f440?)
        /workspace/debug/internal/gocore/object.go:257 +0x3f
golang.org/x/debug/internal/gocore.walkRootTypePtrs(0xc0002ca000, 0xc007396480, {0xc00b28d718, 0x8, 0x8}, 0x0, 0xc00826cea0?, 0xc00b28d720)
        /workspace/debug/internal/gocore/root.go:163 +0x2ab
golang.org/x/debug/internal/gocore.(*Process).forEachRootPtr(...)
        /workspace/debug/internal/gocore/object.go:269
golang.org/x/debug/internal/gocore.(*Process).ForEachRootPtr(0xc00017e300?, 0xa6acf5?, 0x3?)
        /workspace/debug/internal/gocore/object.go:254 +0x4b
main.runHistogram(0xc00017e300?, {0xeffd80?, 0x4?, 0xa6b4df?})
        /workspace/debug/cmd/viewcore/main.go:483 +0x1fb
github.com/spf13/cobra.(*Command).execute(0xed62e0, {0xeffd80, 0x0, 0x0})
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:944 +0x843
github.com/spf13/cobra.(*Command).ExecuteC(0xc000187208)
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:992
main.runRoot.func2()
        /workspace/debug/cmd/viewcore/main.go:361 +0x7c
main.capturePanic(0xb32820?)
        /workspace/debug/cmd/viewcore/main.go:376 +0x51
main.runRoot(0xed5760, {0xc00012a860?, 0x4?, 0xa6b4df?})
        /workspace/debug/cmd/viewcore/main.go:358 +0x672
github.com/spf13/cobra.(*Command).execute(0xed5760, {0xc0001300a0, 0x2, 0x2})
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:944 +0x843
github.com/spf13/cobra.(*Command).ExecuteC(0xed5760)
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
        /gopath/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:992
main.main()
        /workspace/debug/cmd/viewcore/main.go:244 +0x132

What did you expect to see?

Expected program to parse core file gracefully

[gabyhelp]

Related Issues

• x/debug/cmd/viewcore: cannot read core dump -- nil pointer in (*heapInfo).IsPtr() #44637
• x/tools/go/packages: nil pointer dereference #69524 (closed)
• x/debug/cmd/viewcore: panic on reading goroutines #33661 (closed)
• go/types: nil pointer dereference in go/types.(*StdSizes).Sizeof #62167 (closed)
• x/debug/cmd/viewcore: panic on missing pctab entry #27323 (closed)
• runtime: ReadMemStats crashes with segmentation violation #61158 (closed)
• x/debug/cmd/viewcore: NPE in readDebugInfo #44757
• cmd/go: panic: runtime error: invalid memory address or nil pointer dereference during type checking in `go generate` #66670 (closed)
• x/debug: viewcore tool don't support dumps with go1.13.3+ #38638 (closed)
• go/types: nil pointer exception in Checker.allowVersion #61822 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[dr2chase]

@golang/compiler
Looks like people are using viewcore, yay.

[cherrymui]

What version of viewcore are you using? Have you tried the latest version? Thanks.