go-delve/delve · error

malformed executable

Error message

malformed executable

What it means

After resolving the compile unit for a location entry, LocationCovers reads the legacy .debug_loc list through image.loclist2. If the image is nil or its loclist2 reader is empty there is no location list data to walk, so Delve reports the executable as malformed. This catches images whose DIEs reference loclists that don't exist.

Source

Thrown at pkg/proc/bininfo.go:1385

		return [][2]uint64{{0, ^uint64(0)}}, nil
	}

	off, ok := a.(int64)
	if !ok {
		return nil, fmt.Errorf("attribute %s of unsupported type %T", attr, a)
	}
	cu := bi.Images[0].findCompileUnitForOffset(entry.Offset)
	if cu == nil {
		return nil, errors.New("could not find compile unit")
	}
	if cu.Version >= 5 && cu.image.loclist5 != nil {
		return nil, errors.New("LocationCovers does not support DWARFv5")
	}

	image := cu.image
	base := cu.lowPC
	if image == nil || image.loclist2.Empty() {
		return nil, errors.New("malformed executable")
	}

	r := [][2]uint64{}
	var e loclist.Entry
	image.loclist2.Seek(int(off))
	for image.loclist2.Next(&e) {
		if e.BaseAddressSelection() {
			base = e.HighPC
			continue
		}
		r = append(r, [2]uint64{e.LowPC + base, e.HighPC + base})
	}
	return r, nil
}

// Location returns the location described by attribute attr of entry.
// This will either be an int64 address or a slice of Pieces for locations
// that don't correspond to a single memory address (registers, composite

View on GitHub (pinned to a23773e6c3)

Solutions

1. Rebuild or re-obtain the binary with complete DWARF sections
2. Run readelf -S / objdump --dwarf=loc to verify .debug_loc is present and non-empty
3. Keep the separate debug file together with the stripped binary (debuglink must resolve)
4. Re-download the binary if it was corrupted in transit

Example fix

// before
strip --strip-debug -o app app   // may leave dangling loclist refs
// after
objcopy --only-keep-debug app app.debug && strip app && objcopy --add-gnu-debuglink=app.debug app

func hasLoclistData(ef *elf.File) bool {
    s := ef.Section(".debug_loc")
    return s != nil && s.Size > 0
}

if ranges, err := LocationCovers(...); err != nil && err.Error() == "malformed executable" {
    // verify/recover the binary: re-download or reinstall debug file
}

When it happens

Trigger: A DWARF DIE references a .debug_loc offset but the image has an empty/missing .debug_loc section; partially stripped binaries where sections were removed but DIE references remain.

Common situations: Aggressively stripped or section-trimmed binaries (strip removing .debug_loc only); corrupted downloads of executables; custom build pipelines that drop sections post-link.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• ErrNoDebugInfoFound
• LocationCovers does not support DWARFv5
• could not read debug info (%v) and could not read go symbol
• ErrStackUnderflow
• ErrStackIndexOutOfBounds

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/246f8dbdb089bc1f. Report an issue: GitHub.