cmd/link: panic on NetBSD 9/i386

[bsiegert]

Go version

go version 1.25.5 netbsd/386

Output of go env in your module/workspace:

N/A (this is on a CI machine that I do not have direct access to)

What did you do?

In one of the latest NetBSD 386 bulk builds (https://releng.netbsd.org/bulktracker/pkg/74236393), I see multiple Go packages where the linker panics during the build.

What did you see happen?

For example in go-swagger:

github.com/go-swagger/go-swagger/cmd/swagger
# github.com/go-swagger/go-swagger/cmd/swagger
panic: runtime error: index out of range [-7]

goroutine 543 [running]:
cmd/link/internal/ld.(*Link).findfunctab.func1(0x8806ea8, 0x7efad)
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/pcln.go:915 +0x72c
cmd/link/internal/ld.writeBlock(0x8806ea8, 0x9880900, 0x897e008, {0xc8d82d0, 0x29a4, 0x29a4}, 0x8c7f148, 0x1cc898, {0x85c38e0, 0x200, ...})
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1129 +0x58e
cmd/link/internal/ld.writeBlocks.func1(0x9880900, 0x897e008, {0xc8d82d0, 0x29a4, 0x29a4}, 0x8c7f148, 0x1cc898, {0x85c38e0, 0x200, 0x200})
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1080 +0x8c
created by cmd/link/internal/ld.writeBlocks in goroutine 514
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1079 +0x606
*** Error code 1

golangci-lint:

# github.com/golangci/golangci-lint/v2/cmd/golangci-lint
panic: runtime error: index out of range [-7]

goroutine 1352 [running]:
cmd/link/internal/ld.(*Link).findfunctab.func1(0x8882488, 0x106cd9)
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/pcln.go:915 +0x72c
cmd/link/internal/ld.writeBlock(0x8882488, 0x9833b00, 0x89fc008, {0x11660c8c, 0x4acb, 0x4acb}, 0x97bb84c, 0x2ba5f4, {0x85c38e0, 0x200, ...})
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1129 +0x58e
cmd/link/internal/ld.writeBlocks.func1(0x9833b00, 0x89fc008, {0x11660c8c, 0x4acb, 0x4acb}, 0x97bb84c, 0x2ba5f4, {0x85c38e0, 0x200, 0x200})
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1080 +0x8c
created by cmd/link/internal/ld.writeBlocks in goroutine 1283
	/pbulk/work/lang/go125/work/go/src/cmd/link/internal/ld/data.go:1079 +0x606
*** Error code 1

These are the same crash. Any ideas?

What did you expect to see?

I expect to see a successful build, of course. I have not seen these crashes on other architectures, so maybe it's 386-specific?

/cc @golang/netbsd

[gabyhelp]

Related Issues

• cmd/link: panic: runtime error: index out of range #10718 (closed)
• cmd/link: build broken on plan9/amd64 since CL 20928 #14894 (closed)
• cmd/link: "panic: index out of range" on go tip linker #22941 (closed)
• cmd/link: runtime error: index out of range #11186 (closed)
• cmd/link: panic with `index out of range` in `cmd/link/internal/loader.(*Loader).resolve` #62355
• runtime,cmd/compile: frequent memory corruption on NetBSD and OpenBSD since 2021-10-11 #49209 (closed)
• cmd/link/internal/loader: panic: runtime error: index out of range [1232602353] with length 116 #69214 (closed)
• cmd/link: nil pointer panic during compile for openbsd/mips64 #58240 (closed)
• freebsd: cmd/link/internal/loader: panic: runtime error: index out of range [192] with length 3 #50083 (closed)
• cmd/link: index out of range at cmd/link/internal/ld.decodetypeKind #62156 (closed)

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[dr2chase]

@ianlancetaylor any ideas? This smells of "not looking carefully for pclntab, surprised when it moved".

[ianlancetaylor]

This bug report is for Go 1.25.5, which precedes any of my recent linker changes.

The crash is happening when writing out the function table that maps a PC to a function. The fact that the slice index is negative implies that the text symbols are not sorted by address. Or, it implies that the address are larger than 0x80000000. Given that this is happening only on 32-bit systems, I suppose the latter is perhaps more likely.

I can't see any reason why this would be NetBSD-specific. But I'm not able to recreate the problem on Linux, either with Go 1.25 or main. Are you able to reproduce this on NetBSD with a standard Go install? Does the NetBSD Go toolchain have any local patches, perhaps using a larger default text address?