Errors in debugger

[gitd8b]

Hey all,

I'm trying to actively study Ghidra and have run into a roadblock. From following a book, I ran into a weird error. I've gone as far as create a python environment which contains only the built python scripts found in the repo (for version 12.1) and it seems this error still persists whether with the host override whl installs or the virtual environment. I can't seem to find any reports of this online anywhere either, so feels really odd to see this.

The issue is that I'm trying to run the debugger option but get exceptions. I created a breakpoint and went to start a session with gdb + ssh. Due to the constant issues, I have been now trying just gdb in the menu... but still same issues. I should mention, running gdb directly in the terminal on these binaries works perfectly fine. For Ghidra, it throws the following output below into the terminal each time I try to run it. Has anyone else run into this or have suggestions on a fix?

GNU gdb (Debian 17.2-1) 17.2
Copyright (C) 2025 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
The target architecture is set to "i386:x86-64".
The target endianness is set automatically (currently little endian).
Reading symbols from /home/kali/Documents/Practice/GhidraBookCode2e/ch06/compute...
(No debugging symbols found in /home/kali/Documents/Practice/GhidraBookCode2e/ch06/compute)
Connected to Ghidra 12.1 at localhost:12345
Starting program: /home/kali/Documents/Practice/GhidraBookCode2e/ch06/compute 

Program stopped.
0x00007ffff7fe3d40 in ?? () from /lib64/ld-linux-x86-64.so.2
Traceback (most recent call last):
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/arch.py", line 268, in map_value
    av = self.convert_value(value)
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/arch.py", line 262, in convert_value
    result = bytes(cv[i] for i in it)
gdb.error: value is not available

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/hooks.py", line 169, in _func
    return func(*args, **kwargs)
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/hooks.py", line 336, in on_stop
    state.record("Stopped")
    ~~~~~~~~~~~~^^^^^^^^^^^
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/hooks.py", line 98, in record
    commands.putreg(
    ~~~~~~~~~~~~~~~^
        frame, util.get_register_descs(frame.architecture(), 'general'))
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/commands.py", line 632, in putreg
    rv = mapper.map_value(inf, desc.name, v)
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/arch.py", line 306, in map_value
    rv = super().map_value(inf, name, value)
  File "/home/kali/.local/lib/python3.13/site-packages/ghidragdb/arch.py", line 270, in map_value
    raise gdb.GdbError(
        f"Cannot convert {name}'s value: '{value}', type: '{value.type}'")
gdb.GdbError: Cannot convert pl3_ssp's value: '<unavailable>', type: 'void *'
Python Exception <class 'gdb.GdbError'>: Cannot convert pl3_ssp's value: '<unavailable>', type: 'void *'
(gdb) 

[d-millar]

Looks like we need some extra logic to support the "unavailable" return value for some of the newer registers. Are you using an Intel implementation of gdb that could support pl3_ssp or the default Debian package (which presumably now does not but returns "unavailable" as a place marker)?

[nsadeveloper789]

Wonderful. So, I acquired the gdb-17.2 source and built it on my system, but I do not see the p13_ssp register, so I might use some configuration hints, if you got 'em. Otherwise, I'll keep poking around. In the meantime, I do see a new attribute GdbValue.is_unavailable, which I imagine will be helpful in sorting this out; however, that attribute doesn't exist in gdb-16.3. sigh. Might be easiest to maintain broad support by just try-excepting each registers' conversion and skip failures. We already set the value as a string attribute in the Model tree, so the users should see <unavailable> there. It's just the conversion to raw bytes and the setting of the register value in the trace's MemoryManager that'd be skipped.

[nsadeveloper789]

I can't yet reproduce the issue, but I believe this would fix it, if you want to give it a spin:

diff --git a/Ghidra/Debug/Debugger-agent-gdb/src/main/py/src/ghidragdb/commands.py b/Ghidra/Debug/Debugger-agent-gdb/src/main/py/src/ghidragdb/commands.py
index 376db6d4c5..f6937c3b97 100644
--- a/Ghidra/Debug/Debugger-agent-gdb/src/main/py/src/ghidragdb/commands.py
+++ b/Ghidra/Debug/Debugger-agent-gdb/src/main/py/src/ghidragdb/commands.py
@@ -633,12 +633,15 @@ def putreg(frame: gdb.Frame, reg_descs: Sequence[
     # NB: This command will fail if the process is running
     for desc in reg_descs:
         v = frame.read_register(desc.name)
-        rv = mapper.map_value(inf, desc.name, v)
-        values.append(rv)
-        # Mapper has converted to big endian.
-        # Display value should interpret it as such.
-        value = hex(int.from_bytes(rv.value, byteorder='big'))
-        cobj.set_value(desc.name, str(value))
+        try:
+            rv = mapper.map_value(inf, desc.name, v)
+            values.append(rv)
+            # Mapper has converted to big endian.
+            # Display value should interpret it as such.
+            value = hex(int.from_bytes(rv.value, byteorder='big'))
+            cobj.set_value(desc.name, str(value))
+        except Exception as e:
+            cobj.set_value(desc.name, str(v))
         keys.append(desc.name)
     cobj.retain_values(keys)
     # TODO: Memorize registers that failed for this arch, and omit later.

[zax71]

Just adding, I can reproduce this issue on a NixOS install of Ghidra.

[nsadeveloper789]

Does the suggested patch above resolve it? You can patch in an installation without rebuilding, but the file path will be a bit different: Ghidra/Debug/Debugger-agent-gdb/pypkg/src/ghidragdb/commands.py. (...Well, maybe not on Nix)

[amd64-little]

@nsadeveloper789 I have applied the patch you suggested above, and I can confirm it resolves the issue. Let me know if you need any information about my system.

[nsadeveloper789]

Excellent. Thanks for doing that. I believe it's already merged into our dev branch (2762e07), so it should land in 12.2.