为什么 __libc_start_main 的地址在 GDB 中始终相同，即使 ASLR 已打开？

Question

Breakpoint 1, 0x00007ffff7de8060 in __libc_start_main () from /usr/lib/libc.so.6
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/firstlove/projects/org-ioslide/example/a.out 

Breakpoint 1, 0x00007ffff7de8060 in __libc_start_main () from /usr/lib/libc.so.6
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/firstlove/projects/org-ioslide/example/a.out 

Breakpoint 1, 0x00007ffff7de8060 in __libc_start_main () from /usr/lib/libc.so.6
(gdb) Quit
(gdb) quit
A debugging session is active.

        Inferior 1 [process 16372] will be killed.

Quit anyway? (y or n) y
firstlove-pc% cat /proc/sys/kernel/randomize_va_space
2

IIUC，ASLR应该随机分配所有地址，包括其中之一libc.so，但我发现地址__libc_start_main()总是0x00007ffff7de8060在我的Linux机器上，为什么？怎么了？

Answer 1

当您在 中运行程序时gdb，会gdb尝试通过禁用地址随机化来帮助您进行调试。您可以使用以下命令启用它（从程序的下一次运行开始生效）：

set disable-randomization off