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cmd/link: nil pointer panic during compile for openbsd/mips64 #58240

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calmh opened this issue Feb 2, 2023 · 8 comments
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cmd/link: nil pointer panic during compile for openbsd/mips64 #58240

calmh opened this issue Feb 2, 2023 · 8 comments
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@thanm
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arch-mips compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge help wanted NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. OS-OpenBSD
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@calmh
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calmh commented Feb 2, 2023

Noticed this on Go 1.19.5, after updating a few dependencies to support Go 1.20.

% docker run -it --rm golang:1.19.5
root@d0d4ee0380ce:/go# go version
go version go1.19.5 linux/arm64
(issue also happens on linux/amd64)
root@d0d4ee0380ce:/go# git clone -b linkercrash https://github.com/calmh/syncthing.git
(repo clones)
root@d0d4ee0380ce:/go# cd syncthing/
root@d0d4ee0380ce:/go/syncthing# GOOS=openbsd GOARCH=mips64 go build ./cmd/stdiscosrv/
(build happens)
# github.com/syncthing/syncthing/cmd/stdiscosrv
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x15447c]

goroutine 1 [running]:
cmd/link/internal/ld.dynrelocsym(0x40000bc000, 0x2510c?)
	/usr/local/go/src/cmd/link/internal/ld/data.go:853 +0x28c
cmd/link/internal/ld.(*dodataState).dynreloc(0x40006b1b00, 0x40000bc000)
	/usr/local/go/src/cmd/link/internal/ld/data.go:871 +0x8c
cmd/link/internal/ld.(*Link).dodata(0x40000bc000, {0x4002380000, 0x4b89f, 0x4b89f})
	/usr/local/go/src/cmd/link/internal/ld/data.go:1498 +0x384
cmd/link/internal/ld.Main(_, {0x8, 0x20, 0x1, 0x1d, 0x1f, 0x0, {0x0, 0x0}, {0x271699, ...}, ...})
	/usr/local/go/src/cmd/link/internal/ld/main.go:336 +0x12f8
main.main()
	/usr/local/go/src/cmd/link/main.go:72 +0xe98
root@d0d4ee0380ce:/go/syncthing#
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Feb 2, 2023
@mknyszek
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mknyszek commented Feb 2, 2023

CC @golang/compiler

@mknyszek
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mknyszek commented Feb 2, 2023

CC @golang/mips @golang/openbsd

@mknyszek mknyszek added this to the Backlog milestone Feb 2, 2023
@mknyszek mknyszek added NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. help wanted labels Feb 2, 2023
@cuonglm
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cuonglm commented Feb 9, 2023

The CL https://go-review.googlesource.com/c/go/+/233523 introduces this behavior cc @thanm

Pre-CL, that would be a fatal error.

@thanm thanm self-assigned this Feb 9, 2023
@thanm
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thanm commented Feb 9, 2023

I'll take a look.

@thanm
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thanm commented Feb 9, 2023

@calmh looks like this is actually expected behavior given the current state of openbsd + mips64.

What is happening here is that the code in the golang.org/x/sys repo has moved forward with switching OpenBSD to use libc as opposed to directly syscall invocation.

The app in question has a reachable calll to golang.org/x/sys/unix.mmap, which results in the following chain of dependent functions being pulled in (this is from the linker's -dumpdep flag):

golang.org/x/sys/unix.mmap -> golang.org/x/sys/unix.libc_mmap_trampoline_addr
golang.org/x/sys/unix.libc_mmap_trampoline_addr -> libc_mmap_trampoline
libc_mmap_trampoline -> libc_mmap

where libc_mmap is of type SDYNIMPORT (meaning that at runtime its definition will be appearing in a shared library).

The problem here is that although golang.org/x/sys/unix has moved ahead, the CLs to support this in the Go linker are stalled. See the stack at https://go.dev/cl/415815 and successors.

It's unfortunate that the golang.org/x/sys/unix change was rolled out before things were ready in the Go linker realm, but it appears that's just what was decided by the OpenBSD maintainers.

I will send a CL to change things so that we get an error in this case as opposed to a crash, but until https://go.dev/cl/415815 and friends are merged, folks will see these same sorts of errors.

@thanm
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thanm commented Feb 9, 2023

@4a6f656c FYI

@gopherbot
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Change https://go.dev/cl/466895 mentions this issue: cmd/link: improve error for missing SDYNIMPORT support on mips/mips64

johanbrandhorst pushed a commit to Pryz/go that referenced this issue Feb 12, 2023
@thanm @johanbrandhorst
cmd/link: improve error for missing SDYNIMPORT support on mips/mips64
cee497e 
Issue an error (instead of crashing) when encountering a symbol that
requires dynamic relocations on mips/mips64. The dynimport support is
in progress, but is not done yet, so rather than crashing, print a
message indicating that the feature is not yet implemented and exit.

Fixes golang#58240.

Change-Id: I9ad64c89e4f7b4b180964b35ad1d72d375f2df7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/466895
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
@thanm thanm mentioned this issue Feb 21, 2023
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pojntfx added a commit to pojntfx/hydrapp that referenced this issue Feb 24, 2023
@pojntfx
fix: Blocklist openbsd/mips64 due to golang/go#58240
14046e8
pojntfx added a commit to pojntfx/hydrapp that referenced this issue Feb 26, 2023
@pojntfx
fix: Blocklist openbsd/mips64 due to golang/go#58240
1dee195
@sylr
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sylr commented Apr 11, 2023

I reproduced this today with go1.20.3. Using gotip yields another error now:

go1.20.3

$ CGO_ENABLED=0 GOOS=openbsd GOARCH=mips64 go build -tags static,crossbuild -trimpath -ldflags '-s -w -X sigs.k8s.io/kustomize/api/provenance.version=v5.0.1+sylr.1 -X sigs.k8s.io/kustomize/api/provenance.gitCommit=eec6096dd087154c2222b8797f3c7aca6aeb5246 -X sigs.k8s.io/kustomize/api/provenance.buildDate=2023-04-11T09:18:43Z -extldflags ""' -o ../dist/kustomize-v5.0.1+sylr.1-openbsd-mips64
# sigs.k8s.io/kustomize/kustomize/v5
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x101008748]

goroutine 1 [running]:
cmd/link/internal/ld.dynrelocsym(0x1400014c000, 0x1400051e000?)
	/opt/homebrew/Cellar/go/1.20.3/libexec/src/cmd/link/internal/ld/data.go:917 +0x288
cmd/link/internal/ld.(*dodataState).dynreloc(0x1400061a000, 0x1400014c000)
	/opt/homebrew/Cellar/go/1.20.3/libexec/src/cmd/link/internal/ld/data.go:935 +0x8c
cmd/link/internal/ld.(*Link).dodata(0x1400014c000, {0x14001980000, 0x5d87e, 0x5d87e})
	/opt/homebrew/Cellar/go/1.20.3/libexec/src/cmd/link/internal/ld/data.go:1566 +0x3b4
cmd/link/internal/ld.Main(_, {0x8, 0x20, 0x1, 0x1d, 0x1f, 0x0, {0x0, 0x0}, {0x1010c8663, ...}, ...})
	/opt/homebrew/Cellar/go/1.20.3/libexec/src/cmd/link/internal/ld/main.go:338 +0x13e4
main.main()
	/opt/homebrew/Cellar/go/1.20.3/libexec/src/cmd/link/main.go:72 +0xcb8

gotip

$ CGO_ENABLED=0 GOOS=openbsd GOARCH=mips64 gotip build -tags static,crossbuild -trimpath -ldflags '-s -w -X sigs.k8s.io/kustomize/api/provenance.version=v5.0.1+sylr.1 -X sigs.k8s.io/kustomize/api/provenance.gitCommit=eec6096dd087154c2222b8797f3c7aca6aeb5246 -X sigs.k8s.io/kustomize/api/provenance.buildDate=2023-04-11T09:18:43Z -extldflags ""' -o ../dist/kustomize-v5.0.1+sylr.1-openbsd-mips64
# sigs.k8s.io/kustomize/kustomize/v5
golang.org/x/sys/unix.ioctl: relocation target syscall.syscall not defined
golang.org/x/sys/unix.read: relocation target syscall.syscall not defined
golang.org/x/sys/unix.mmap: relocation target syscall.syscall6 not defined
golang.org/x/sys/unix.munmap: relocation target syscall.syscall not defined

Commit: sylr/kustomize@eec6096

@peter-mount peter-mount mentioned this issue Jun 21, 2023
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arch-mips compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge help wanted NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. OS-OpenBSD
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@calmh @sylr @mknyszek @cuonglm @gopherbot @thanm