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debug/elf: opening ELF binary with detached debug symbols results in panic #63837

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benbaker76 opened this issue Oct 31, 2023 · 1 comment
Closed

debug/elf: opening ELF binary with detached debug symbols results in panic #63837

benbaker76 opened this issue Oct 31, 2023 · 1 comment
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.

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@benbaker76
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benbaker76 commented Oct 31, 2023 •
edited

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

$ go version
go version go1.21.3 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output
$ go env
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/bbaker/.cache/go-build'
GOENV='/home/bbaker/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/bbaker/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/bbaker/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/bbaker/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/bbaker/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.3'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/bbaker/Programming/bpf/libbpf-tools/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3402554320=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I want to examine an ELF binary with detached debug symbols. I was looking for the offset and size of _int_malloc in /usr/lib/x86_64-linux-gnu/libc.so.6.

$ readelf -sW /usr/lib/x86_64-linux-gnu/libc.so.6 | grep _int_malloc
$ readelf --notes /usr/lib/x86_64-linux-gnu/libc.so.6 | grep -A 3 .note.gnu.build-id
Displaying notes found in: .note.gnu.build-id
  Owner                Data size 	Description
  GNU                  0x00000014	NT_GNU_BUILD_ID (unique build ID bitstring)
    Build ID: ff2d8e707625b73b293961a4bc168e373d14a44a
$ dwarfdump --print-debug-names /usr/lib/x86_64-linux-gnu/libc.so.6
Filename by debuglink is /usr/lib/debug/.build-id/ff/2d8e707625b73b293961a4bc168e373d14a44a.debug

.note.gnu.build-id
 Build-id  type     : 3
 Build-id  ownername: GNU
 Build-id  length   : 20
 Build-id           : ff2d8e707625b73b293961a4bc168e373d14a44a
 Possible .gnu_debuglink/.note.gnu.build-id pathnames for
 an alternate object file with more detailed DWARF
  [0] /usr/lib/debug/.build-id/ff/2d8e707625b73b293961a4bc168e373d14a44a.debug
       file above is an Elf object
$ readelf -sW /usr/lib/debug/.build-id/ff/2d8e707625b73b293961a4bc168e373d14a44a.debug | grep _int_malloc
readelf: Error: Unable to find program interpreter name
  1331: 000000000009e360  3738 FUNC    LOCAL  DEFAULT   16 _int_malloc
f, err := elf.Open("/usr/lib/debug/.build-id/ff/2d8e707625b73b293961a4bc168e373d14a44a.debug")
if err != nil {
	fmt.Println("Error opening ELF:", err)
	return
}
defer f.Close()

What did you expect to see?

I should be able to view the debug info in the ELF file.

What did you see instead?

panic: interface conversion: interface {} is nil, not uint64
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Oct 31, 2023
@mauri870 mauri870 added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Oct 31, 2023
@benbaker76 benbaker76 changed the title debug/elf: opening ELF binary with detached debug symbols results in exit status 1 debug/elf: opening ELF binary with detached debug symbols results in error Nov 1, 2023
@benbaker76 benbaker76 changed the title debug/elf: opening ELF binary with detached debug symbols results in error debug/elf: opening ELF binary with detached debug symbols results in panic Nov 1, 2023
@benbaker76
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Turns out it's an issue in my code that was not showing up due to a deferred os.Exit(1)

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