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cmd/link: crash on undef symbol when external linking #47993

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thanm opened this issue Aug 26, 2021 · 1 comment
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cmd/link: crash on undef symbol when external linking #47993

thanm opened this issue Aug 26, 2021 · 1 comment
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@thanm
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@thanm thanm commented Aug 26, 2021

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

Using tip.

$ go version
go version devel go1.18-b5498bb297 Thu Aug 26 15:07:04 2021 -0400 linux/amd64

Does this issue reproduce with the latest release?

yes

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

linux/amd64

What did you do?

Build this code:

package main

type M struct {
	b bool
}

func (m *M) run(fp func())

func doit(m *M) {
	m.run(func() {
	})
}

func main() {
	m := &M{true}
	doit(m)
}

with

go build -ldflags="-linkmode=external" m.go

What did you expect to see?

Error about main.(*M).run being undefined, but no crash.

What did you see instead?

Crash with:

# command-line-arguments
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x5509b6]

goroutine 34 [running]:
cmd/link/internal/ld.(*relocSymState).relocsym(0xc00016ee98, 0x7, {0x7f4fb3f3ef60, 0x58, 0x1603e5})
	/w/ygo/src/cmd/link/internal/ld/data.go:441 +0x1816
cmd/link/internal/ld.writeBlock(0xc000150000, 0xc000e937b0, 0xc000586000, {0xc000172000, 0xdd1, 0x0}, 0xc000135598, 0x0, {0x86b240, 0x200, ...})
	/w/ygo/src/cmd/link/internal/ld/data.go:995 +0x390
cmd/link/internal/ld.writeBlocks.func1(0xc000ff1000, 0x44d, {0xc000172000, 0x60000c000e937d0, 0x12}, 0xc000e88250, 0xc000158d80, {0x86b240, 0x200, 0x200})
	/w/ygo/src/cmd/link/internal/ld/data.go:951 +0x76
created by cmd/link/internal/ld.writeBlocks
	/w/ygo/src/cmd/link/internal/ld/data.go:950 +0x57c
@thanm thanm self-assigned this Aug 26, 2021
@gopherbot
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@gopherbot gopherbot commented Aug 26, 2021

Change https://golang.org/cl/345473 mentions this issue: cmd/link: avoid crash on undefined func sym with external linking

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@gopherbot gopherbot closed this in 014a972 Sep 2, 2021
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