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Date: Wed, 18 Jul 2018 21:38:34 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: Re: Segmentation fault in static binaries built with
recent binutils
* Szabolcs Nagy <nsz@...t70.net> [2018-07-18 21:00:24 +0200]:
> * Reiner Herrmann <reiner@...ner-h.de> [2018-07-18 20:14:38 +0200]:
> > > Can you attach a readelf -a of the binary that's crashing?
> >
> > The output is attached.
>
> i could reproduce the crash in a debian:unstable docker image
>
> i see incorrect auxv[AT_PHDR] value, not yet sure why.
>
>
> Program received signal SIGSEGV, Segmentation fault.
> static_init_tls (aux=aux@...ry=0x7fffffffebc0) at ../src/env/__init_tls.c:88
> 88 if (phdr->p_type == PT_PHDR)
> (gdb) disas
> Dump of assembler code for function static_init_tls:
> 0x0000000000401404 <+0>: sub $0x8,%rsp
> 0x0000000000401408 <+4>: mov 0x18(%rdi),%r9
> 0x000000000040140c <+8>: mov 0x28(%rdi),%rsi
> 0x0000000000401410 <+12>: xor %ecx,%ecx
> 0x0000000000401412 <+14>: xor %eax,%eax
> 0x0000000000401414 <+16>: mov %r9,%rdx
> 0x0000000000401417 <+19>: test %rsi,%rsi
> 0x000000000040141a <+22>: je 0x401456 <static_init_tls+82>
> => 0x000000000040141c <+24>: mov (%rdx),%r8d
> ...
> (gdb) p/x aux[3]
> $4 = 0x400040
> (gdb) i proc map
> process 13499
> Mapped address spaces:
>
> Start Addr End Addr Size Offset objfile
> 0x401000 0x402000 0x1000 0x1000 /musl/build/a.out
> 0x402000 0x403000 0x1000 0x2000 /musl/build/a.out
> 0x403000 0x405000 0x2000 0x2000 /musl/build/a.out
> 0x7ffff7ffa000 0x7ffff7ffd000 0x3000 0x0 [vvar]
> 0x7ffff7ffd000 0x7ffff7fff000 0x2000 0x0 [vdso]
> 0x7ffffffde000 0x7ffffffff000 0x21000 0x0 [stack]
seems like another musl-gcc wrapper issue, if i do the linking
manually then i get a working binary, havent yet figured out why
manual linking:
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x0000000000400000 0x0000000000400000 0x0001ec 0x0001ec R 0x1000
LOAD 0x001000 0x0000000000401000 0x0000000000401000 0x0005a4 0x0005a4 R E 0x1000
LOAD 0x002000 0x0000000000402000 0x0000000000402000 0x00004c 0x00004c R 0x1000
LOAD 0x002ff0 0x0000000000403ff0 0x0000000000403ff0 0x000018 0x0002a8 RW 0x1000
NOTE 0x0001c8 0x00000000004001c8 0x00000000004001c8 0x000024 0x000024 R 0x4
GNU_STACK 0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW 0x10
GNU_RELRO 0x002ff0 0x0000000000403ff0 0x0000000000403ff0 0x000010 0x000010 R 0x1
musl-gcc linking:
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x001000 0x0000000000401000 0x0000000000401000 0x0005a4 0x0005a4 R E 0x1000
LOAD 0x002000 0x0000000000402000 0x0000000000402000 0x00004c 0x00004c R 0x1000
LOAD 0x002ff0 0x0000000000403ff0 0x0000000000403ff0 0x000018 0x0002a8 RW 0x1000
GNU_STACK 0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW 0x10
GNU_RELRO 0x002ff0 0x0000000000403ff0 0x0000000000403ff0 0x000010 0x000010 R 0x1
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