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Message-ID: <CACT4Y+b53dDLCqA1wq02a26b7mpmb6Pag9BQaRE0x3OSnCY5tg@mail.gmail.com>
Date: Sat, 1 Mar 2025 16:08:52 +0100
From: Dmitry Vyukov <dvyukov@...gle.com>
To: musl@...ts.openwall.com
Subject: Support for -static-pie relocations
Hello,
This simple program crashes when compiled with -static-pie:
#include <stdio.h>
int main() { fprintf(stderr, "Hello\n"); }
Program received signal SIGSEGV, Segmentation fault.
0x0000000000001170 in ?? ()
(gdb) bt
#0 0x0000000000001170 in ?? ()
#1 0x00007ffff7ffb3b8 in libc_start_init () at src/env/__libc_start_main.c:64
#2 0x00007ffff7ffb3e8 in libc_start_main_stage2 (main=0x7ffff7ffb180
<main>, argc=1, argv=0x7fffffffdc98)
at src/env/__libc_start_main.c:92
#3 0x00007ffff7ffb0b1 in _start ()
(gdb) up
#1 0x00007ffff7ffb3b8 in libc_start_init () at src/env/__libc_start_main.c:64
64 (*(void (**)(void))a)();
(gdb) disass
Dump of assembler code for function libc_start_init:
0x00007ffff7ffb39b <+0>: push %rbp
0x00007ffff7ffb39c <+1>: push %rbx
0x00007ffff7ffb39d <+2>: sub $0x8,%rsp
0x00007ffff7ffb3a1 <+6>: call 0x7ffff7ffb000 <_init>
0x00007ffff7ffb3a6 <+11>: lea 0x2a9b(%rip),%rbx # 0x7ffff7ffde48
0x00007ffff7ffb3ad <+18>: lea 0x2a9c(%rip),%rbp # 0x7ffff7ffde50
0x00007ffff7ffb3b4 <+25>: jmp 0x7ffff7ffb3bc <libc_start_init+33>
0x00007ffff7ffb3b6 <+27>: call *(%rbx)
=> 0x00007ffff7ffb3b8 <+29>: add $0x8,%rbx
0x00007ffff7ffb3bc <+33>: cmp %rbp,%rbx
0x00007ffff7ffb3bf <+36>: jb 0x7ffff7ffb3b6 <libc_start_init+27>
0x00007ffff7ffb3c1 <+38>: add $0x8,%rsp
0x00007ffff7ffb3c5 <+42>: pop %rbx
0x00007ffff7ffb3c6 <+43>: pop %rbp
0x00007ffff7ffb3c7 <+44>: ret
End of assembler dump.
(gdb) p /x $rbx
$1 = 0x7ffff7ffde48
(gdb) p /x *(void**)$rbx
$2 = 0x1170
This 0x1170 is probably a ctor pointer offset that wasn't relocated.
A fix would probably be calling _dl_relocate_object() somewhere on the
__libc_start_main() path.
Is there a reason this is not supported? Or merely not implemented yet?
Can't find an issue tracker nor searchable archives for previous
discussions on this...
Thanks in advance
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