了解分段故障的堆栈跟踪 [英] understanding stack trace of a segmentation fault

问题描述

我正在执行 snprintf 并遇到段错误.

I am doing an snprintf and getting a seg fault.

当我像这样将核心文件加载到gdb上时: gdb my_executable core ；并做了 bt 来获取回溯，我得到了:

when I loaded the core file on gdb like this: gdb my_executable core ; and did bt to get the backtrace, I got following:

Program terminated with signal 11, Segmentation fault.
#0  0x88207fc2 in memcpy () from /usr/lib/libc.so.6
(gdb) bt
#0  0x88207fc2 in memcpy () from /usr/lib/libc.so.6
#1  0x88205eb6 in __sfvwrite () from /usr/lib/libc.so.6
#2  0x881fbc95 in strchr () from /usr/lib/libc.so.6
#3  0xbfbe6c14 in ?? ()
#4  0xbfbe69d8 in ?? ()
#5  0x881ed91e in localeconv () from /usr/lib/libc.so.6
#6  0x881fec05 in __vfprintf () from /usr/lib/libc.so.6
#7  0x881f7d80 in snprintf () from /usr/lib/libc.so.6  
#8  0x08052b64 in my_function (files=0xbfbed710, filename=<value optimized out>) at myfile.c:1102
#9  0x08053bfb in main (argc=4, argv=0xbfbedd90) at myfile.c:225

在出现段错误的情况下，我会多次看到这样的堆栈，但从未正确理解.

I see such stack many times in case of seg fault but never understood correctly.

仅查看跟踪中的呼叫，我们就能知道出了什么问题吗?

Just looking the calls in trace, can we tell what is going wrong?

注意:请不要索取更多代码.我的动机只是简单地理解这样的堆栈跟踪意味着什么-与代码无关.我看到最上面的"memcpy"失败了.我想了解在这种情况下何时会发生这种情况.

NOTE: Please do not ask for more code. My motive is simply understand what the stack-trace like this means - irrespective of code. I see that on the top "memcpy" is failing. I want to understand when that can happen in this situation.

推荐答案

您的函数在 myfile.c:1102 处执行了某些操作.反过来，这会欺骗标准库，使其非法访问内存.操作系统会通过 sigsegv 注意到并拍打您的程序.

You function does something at myfile.c:1102. This in turn tricks the standard library into illegally accessing memory. The operating system notices and slaps your program with sigsegv.

常见原因(如Stackoverflow所示))为:

Common reasons, (as seen on Stackoverflow :)) ) are:

• 写到只读存储器
• 使用未初始化的指针
• 访问已分配块末尾的内存

长长的函数列表显示了执行此操作的人.所以:

The long list of functions shows you who did it. So:

• my_function 称为 snprintf
• 调用了 __ vfprintf
• ...

这篇关于了解分段故障的堆栈跟踪的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！