go-delve/delve · error

the specific range has exceeded readable area

Error message

the specific range has exceeded readable area

What it means

This error comes from a helper that reads a fixed-length byte range from the target's memory. The underlying MemoryReadWriter may return fewer bytes than requested even without a hard error (e.g. the range straddles the end of a mapped page). Delve treats a short read as a failure of the requested range and returns this error instead of partial data.

Source

Thrown at service/debugger/debugger.go:2258

	defer d.targetMutex.Unlock()
	return d.target.Selected.BinInfo().Images
}

// ExamineMemory returns the raw memory stored at the given address.
// The amount of data to be read is specified by length.
// This function will return an error if it reads less than `length` bytes.
func (d *Debugger) ExamineMemory(address uint64, length int) ([]byte, error) {
	d.targetMutex.Lock()
	defer d.targetMutex.Unlock()

	mem := d.target.Selected.Memory()
	data := make([]byte, length)
	n, err := mem.ReadMemory(data, address)
	if err != nil {
		return nil, err
	}
	if length != n {
		return nil, errors.New("the specific range has exceeded readable area")
	}
	return data, nil
}

func (d *Debugger) GetVersion(out *api.GetVersionOut) error {
	if d.config.CoreFile != "" {
		if d.config.Backend == "rr" {
			out.Backend = "rr"
		} else {
			out.Backend = "core"
		}
	} else {
		if d.config.Backend == "default" {
			if runtime.GOOS == "darwin" {
				out.Backend = "lldb"
			} else {
				out.Backend = "native"
			}

View on GitHub (pinned to a23773e6c3)

Solutions

1. Reduce the requested length so it stays within one readable mapped region
2. Verify the base address is valid (check the variable/expression that produced it)
3. Use ExamineMemory's region info or `/proc/<pid>/maps` to find readable boundaries
4. Read in smaller chunks and stop at the first short read

Example fix

// before
mem, _ := dbg.ExamineMemory(&api.ExamineMemoryIn{Address: 0xC000000000, Length: 0x10000}) // crosses unmapped gap
// after
mem, _ := dbg.ExamineMemory(&api.ExamineMemoryIn{Address: 0xC000000000, Length: 0x1000}) // stay within mapped page

func safeReadLength(addr uint64, length int64, maxRegion uint64) (int64, bool) {
    if addr >= maxRegion || length <= 0 || addr+uint64(length) > maxRegion {
        return 0, false
    }
    return length, true
}

func readableRange(addr uint64, length int64) bool {
    return length > 0 && addr != 0 && addr < ^uint64(0)-uint64(length)
}

data, err := dbg.examineMemory(address, length)
if err != nil && err.Error() == "the specific range has exceeded readable area" {
    // retry with smaller chunk within the mapped region
}

When it happens

Trigger: Calling the memory-reading helper (used by ExamineMemory and similar APIs) with an address/length whose range extends beyond the readable mapped region of the debuggee or core file, so mem.ReadMemory returns n < length.

Common situations: Examining memory at an address computed from a bad/optimized pointer; reading past the end of a heap allocation or unmapped page; core dump analysis where only some pages are present; hexdump commands with oversized lengths.

Related errors

• short read
• can not continue execution of core process
• can not change register values of core process
• unrecognized core format
• cannot write a breakpoint to a core file

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/3b006ed551c0d36b. Report an issue: GitHub.