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Linux内核调试：“ Python异常 <class 'gdb.error'> 尝试在gdb中使用帮助程序脚本时，没有名为module_core的成员。

[英]Linux Kernel Debugging: “Python Exception <class 'gdb.error'> There is no member named module_core.” when trying to use helper scripts in gdb

原文 2018-09-15 16:06:04 1 1 python/ linux-kernel/ gdb/ kernel

I've been following this guide to set up a Linux kernel debugging environment with gdb and VMWare. 我一直遵循本指南来使用gdb和VMWare设置Linux内核调试环境。 Everything went on smoothly until that part: 一切进展顺利，直到那一部分：

Connect GDB to the debuggee 将GDB连接到调试对象
We won't be able to see symbols from loaded kernel modules yet. 我们还无法看到来自已加载内核模块的符号。 We'll load the helper script and then run lx-symbols, which will probe the loaded modules and configure GDB appropriately: 我们将加载帮助程序脚本，然后运行lx-symbols，它将探测已加载的模块并适当地配置GDB：
(gdb) source home/alambert/kernel/source/linux-4.13.0/debian/build/build-generic/vmlinux-gdb.py
(gdb) lx-symbols

When running this on my system I get the following python error: 在系统上运行此命令时，出现以下python错误：
pwndbg> source /home/user/kernel/source/linux-4.4.0/debian/build/build-generic/vmlinux-gdb.py pwndbg> lx-symbols loading vmlinux Python Exception <class 'gdb.error'> There is no member named module_core.: Error occurred in Python command: There is no member named module_core.

My setup 我的设定

Both the debugger and debugee machines are VMs, the debugee is a Ubuntu 16.04 and the debugger is a Ubuntu 18.04. 无论是调试器和被调试机器的虚拟机，被调试是Ubuntu的16.04和调试器是一个Ubuntu的18.04。

Debugee: 被调试者：
$ cat /proc/version Linux version 4.4.0-134-generic (buildd@lgw01-amd64-033) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.10) ) #160-Ubuntu SMP Wed Aug 15 14:58:00 UTC 2018

Debugger: 调试器：
$ cat /proc/version Linux version 4.15.0-34-generic (buildd@lgw01-amd64-047) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #37-Ubuntu SMP Mon Aug 27 15:21:48 UTC 2018 $ gdb --version GNU gdb (GDB) 8.2 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. $ python -V Python 2.7.15rc1

I first thought it was a python3/2 compatibility issue so I recompiled gdb with python 2.7, but got the exact same error. 我首先认为这是python3 / 2兼容性问题，所以我用python 2.7重新编译了gdb，但得到了完全相同的错误。

I have also verified it is not a pwndbg problem - I tried this with vanilla gdb to the exact same effect. 我还验证了这不是pwndbg问题-我尝试使用香草gdb达到完全相同的效果。

I have verified that the python helper scripts had been created in the process of compiling the debugee kernel. 我已经验证了python帮助程序脚本是在编译被调试程序内核的过程中创建的。 I actually let the whole build process complete rather than stopping it once the scripts were created like the guide suggests - just to make sure all of them are in place. 实际上，我让整个构建过程完成了，而不是像指南所建议的那样立即停止了脚本-只是确保所有这些都就位。

I have tried looking for the error online but there does not seem to be any mention of it. 我尝试过在线查找错误，但似乎没有任何提及。

Did anybody ever encounter that problem? 有人遇到过这个问题吗？

1 个解决方案

After some digging in the sources of the scripts and the linux kernel, I have managed to fix the issue. 在深入研究了脚本和linux内核的源代码之后，我设法解决了这个问题。

The problem lies in this commit which replaced the module_core pointer with a module_layout struct in the include/linux/module.h header. 问题就出在此提交它取代了module_core指针与module_layout在struct include/linux/module.h报头。 The change had been apparently pulled into kernel 4.4.0 but was not accounted for in the helper scripts until a later version. 显然，此更改已引入内核4.4.0，但直到更高版本才在帮助程序脚本中进行说明。

This had been dealt with a while later (specifically - in this commit ), so all kernel versions between 4.4.0 and 4.6-rc1 will have this bug. 稍后（特别是在此commit中）对此进行了处理，因此所有4.4.0到4.6-rc1之间的内核版本都将出现此错误。

The solution is to download the scripts from the aforementioned commit and place them in the relevant directories. 解决方案是从上述提交中下载脚本并将它们放置在相关目录中。

This is certainly a rare edge-case but I hope this answer will be helpful to somebody someday. 这当然是一种罕见的极端情况，但是我希望这个答案有一天能对某人有所帮助。