pwndbg fails to work with 64bit kernel in qemu

Description

pwndbg raises when debugging a 64bit stripped kernel. the error message looks like this:

pwndbg: loaded 196 commands. Type pwndbg [filter] for a list.
pwndbg: created $rebase, $ida gdb functions (can be used with print/break)
Reading symbols from ./vmlinux...(no debugging symbols found)...done.
pwndbg> target remote :1234
Remote debugging using :1234
Exception occurred: Error: Cannot access memory at address 0xf81802ff0 (<class 'gdb.MemoryError'>)
For more info invoke `set exception-verbose on` and rerun the command
or debug it by yourself with `set exception-debugger on`
Exception occurred: Error: Cannot access memory at address 0xf81802ff0 (<class 'gdb.MemoryError'>)
For more info invoke `set exception-verbose on` and rerun the command
or debug it by yourself with `set exception-debugger on`
Python Exception <class 'gdb.MemoryError'> Cannot access memory at address 0xf81802ff0: 
^CPython Exception <class 'KeyboardInterrupt'> : 
^CPython Exception <class 'KeyboardInterrupt'> Quit: 
^CPython Exception <class 'KeyboardInterrupt'> Quit: 
0xffffffff8111c398 in ?? ()
^CPython Exception <class 'KeyboardInterrupt'> Quit: 
pwndbg> vmmap
^CPython Exception <class 'KeyboardInterrupt'> Quit: 
Error occurred in Python command: Quit
^CPython Exception <class 'KeyboardInterrupt'> Quit:

Steps to reproduce

1. download the kernel/initfs from https://github.com/mephi42/ctf/blob/master/2021.04.09-Midnight_Sun_CTF_2021_Quals/brohammer/brohammer.tar.gz
2. launch the kernel with command

qemu-system-x86_64 \
    -m 1024M \
    -kernel ./vmlinuz \
    -initrd ./rootfs.img \
    -nographic \
    -monitor /dev/null \
    -append "nokaslr root=/dev/ram rw console=ttyS0 oops=panic paneic=1 quiet" \
    -s

1. extract the vmlinuz to vmlinux
2. run gdb with pwndbg and execute target remote :1234

My setup

I’m using commit 87da998fcefe8cba85f51dba0056b923483c6c1c, which is the latest commit rn. gdb version:

pwndbg> show version
GNU gdb (Ubuntu 8.1.1-0ubuntu1) 8.1.1
Copyright (C) 2018 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:
<http://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".
pwndbg> py import sys; print(sys.version)
3.6.9 (default, Jan 26 2021, 15:33:00) 
[GCC 8.4.0]

[Kyle-Kyle]

Sounds like there was not enough support for kernel debugging. Ok. Challenge accepted.

[Kyle-Kyle]

with a little fix. I think pwndbg works on Linux kernel now.