crash - 使用断点时 gdb 崩溃

Question

在我尝试调试的每个程序中，每次使用断点并尝试运行 gdb 崩溃的任何程序时，我都会得到相同的结果。我在不同的程序上尝试了同样的事情，但它一直这样。

我将显示这个简单的结果:

int main(int argc,char* argv[]){
    for(int i = 0;i < 200; i++){
        printf("%d\n",i);
    }
}

gcc main.c -m32 -std=c99 -o test

GNU gdb (Debian 8.3-1) 8.3
Copyright (C) 2019 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"...
Reading symbols from test...
(No debugging symbols found in test)
(gdb) disas main
Dump of assembler code for function main:
   0x00001199 <+0>: lea    0x4(%esp),%ecx
   0x0000119d <+4>: and    $0xfffffff0,%esp
   0x000011a0 <+7>: pushl  -0x4(%ecx)
   0x000011a3 <+10>:    push   %ebp
   0x000011a4 <+11>:    mov    %esp,%ebp
   0x000011a6 <+13>:    push   %ebx
   0x000011a7 <+14>:    push   %ecx
   0x000011a8 <+15>:    sub    $0x10,%esp
   0x000011ab <+18>:    call   0x10a0 <__x86.get_pc_thunk.bx>
   0x000011b0 <+23>:    add    $0x2e50,%ebx
   0x000011b6 <+29>:    movl   $0x0,-0xc(%ebp)
   0x000011bd <+36>:    jmp    0x11d8 <main+63>
   0x000011bf <+38>:    sub    $0x8,%esp
   0x000011c2 <+41>:    pushl  -0xc(%ebp)
   0x000011c5 <+44>:    lea    -0x1ff8(%ebx),%eax
   0x000011cb <+50>:    push   %eax
   0x000011cc <+51>:    call   0x1030 <printf@plt>
   0x000011d1 <+56>:    add    $0x10,%esp
   0x000011d4 <+59>:    addl   $0x1,-0xc(%ebp)
   0x000011d8 <+63>:    cmpl   $0xc7,-0xc(%ebp)
   0x000011df <+70>:    jle    0x11bf <main+38>
   0x000011e1 <+72>:    mov    $0x0,%eax
   0x000011e6 <+77>:    lea    -0x8(%ebp),%esp
   0x000011e9 <+80>:    pop    %ecx
   0x000011ea <+81>:    pop    %ebx
   0x000011eb <+82>:    pop    %ebp
   0x000011ec <+83>:    lea    -0x4(%ecx),%esp
   0x000011ef <+86>:    ret    
End of assembler dump.
(gdb) break *0x000011ef
Breakpoint 1 at 0x11ef
(gdb) run
Starting program: /root/test 

[1]+  Stopped                 gdb test

我尝试在另一台 Linux 机器上做同样的事情，效果很好。那么可能是什么问题呢？

更新:我找到了断点问题的临时解决方案(这样 gdb 就不会崩溃)，您在开始时使用命令(start)，一切都会正常工作:

GNU gdb (Debian 8.3-1) 8.3
Copyright (C) 2019 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"...
Reading symbols from test...
(No debugging symbols found in test)
(gdb) start
Temporary breakpoint 1 at 0x11a8
Starting program: /root/test 

Temporary breakpoint 1, 0x565561a8 in main ()
(gdb) enable
(gdb) disas main
Dump of assembler code for function main:
   0x56556199 <+0>: lea    0x4(%esp),%ecx
   0x5655619d <+4>: and    $0xfffffff0,%esp
   0x565561a0 <+7>: pushl  -0x4(%ecx)
   0x565561a3 <+10>:    push   %ebp
   0x565561a4 <+11>:    mov    %esp,%ebp
   0x565561a6 <+13>:    push   %ebx
   0x565561a7 <+14>:    push   %ecx
=> 0x565561a8 <+15>:    sub    $0x10,%esp
   0x565561ab <+18>:    call   0x565560a0 <__x86.get_pc_thunk.bx>
   0x565561b0 <+23>:    add    $0x2e50,%ebx
   0x565561b6 <+29>:    movl   $0x0,-0xc(%ebp)
   0x565561bd <+36>:    jmp    0x565561d8 <main+63>
   0x565561bf <+38>:    sub    $0x8,%esp
   0x565561c2 <+41>:    pushl  -0xc(%ebp)
   0x565561c5 <+44>:    lea    -0x1ff8(%ebx),%eax
   0x565561cb <+50>:    push   %eax
   0x565561cc <+51>:    call   0x56556030 <printf@plt>
   0x565561d1 <+56>:    add    $0x10,%esp
   0x565561d4 <+59>:    addl   $0x1,-0xc(%ebp)
   0x565561d8 <+63>:    cmpl   $0xc7,-0xc(%ebp)
   0x565561df <+70>:    jle    0x565561bf <main+38>
   0x565561e1 <+72>:    mov    $0x0,%eax
   0x565561e6 <+77>:    lea    -0x8(%ebp),%esp
   0x565561e9 <+80>:    pop    %ecx
   0x565561ea <+81>:    pop    %ebx
   0x565561eb <+82>:    pop    %ebp
   0x565561ec <+83>:    lea    -0x4(%ecx),%esp
   0x565561ef <+86>:    ret    
End of assembler dump.
(gdb) break *0x565561df
Breakpoint 2 at 0x565561df
(gdb) info break
Num     Type           Disp Enb Address    What
2       breakpoint     keep y   0x565561df <main+70>
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /root/test 

Breakpoint 2, 0x565561df in main ()
(gdb) step
Single stepping until exit from function main,
which has no line number information.
0

Breakpoint 2, 0x565561df in main ()
(gdb) 
Single stepping until exit from function main,
which has no line number information.
1

Breakpoint 2, 0x565561df in main ()
(gdb) 
Single stepping until exit from function main,
which has no line number information.
2

Breakpoint 2, 0x565561df in main ()
(gdb) 
Single stepping until exit from function main,
which has no line number information.
3

Breakpoint 2, 0x565561df in main ()
(gdb) 
Single stepping until exit from function main,
which has no line number information.
4

Breakpoint 2, 0x565561df in main ()

不幸的是，这是一个临时解决方案，只是为了让您可以处理断点，它与崩溃问题无关。

Answer 1

您很可能尝试使用此命令 break *0x000011ef 在无效地址处设置断点。 0x11ef 是该指令在 ELF 内的段内的偏移量，但程序在加载/启动时将被重新定位。

您应该尝试start，然后disas main，然后放置断点。

GDB 像这样停止是当 GDB 在尝试放置断点时抛出错误时发生的错误，它已在上游 GDB 中通过此补丁修复:

https://sourceware.org/ml/gdb-patches/2019-05/msg00361.html

一旦你看到 GDB 像这样停止:

[1]+ 停止了 gdb soQuestionProgram

你应该被扔回 shell。只需使用 fg 命令恢复 GDB 并继续调试 session 。一旦 GDB 8.4 发布，这个错误将被修复。