Clever Geek Handbook

Accessing a corrupted shared library

Here is the code cpuid2.s

:

#cpuid2.s view the cpuid vendor id string using c library calls
.section .data
output:
    .asciz "The processor Vendor ID is '%s'\n"

.section .bss
    .lcomm buffer, 12

.section .text
.global _start
_start:
    movl $0, %eax
    cpuid
    movl $buffer, %edi
    movl %ebx, (%edi)
    movl %edx, 4(%edi)
    movl %ecx, 8(%edi)
    push $buffer
    push $output
    call printf
    addl $8, %esp
    push $0
    call exit

I build, link and run it like this:

as -o cpuid2.o cpuid2.s
ld -dynamic-linker /lib/ld-linux.so.2 -o cpuid2 -lc cpuid2.o
./cpuid2
bash: ./cpuid2: Accessing a corrupted shared library

I searched StackOverflow for this error. I found this question that is similar to mine. And I tried the method given by @rasion. Like this:

as -32 -o cpuid2.o cpuid2.s
ld -melf_i386 -L/lib -lc -o cpuid2 cpuid2.o
ld: cannot find -lc

His answer doesn't solve my problem. Hope someone can help me.

I am using AT&T syntax with GNU assembler.

My computer has 64 bit Ubuntu 14.04.

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2 answers


As you can imagine, you are trying to compile an assembly for a 32-bit machine on a 64-bit machine. With the commands you copied and pasted, you let as

and ld

know that you are compiling something 32-bit.

The problem you are facing is that you don't have a 32 bit libc to reference.

apt-get install libc6:i386 libc6-dev-i386

Then compile the code with:

as --32 -o cpuid2.o cpuid2.s


and finally link it with:

ld -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o cpuid2 -lc cpuid2.o

Then it should work:

[jkominek@kyatt /tmp]$ ./cpuid2 
The processor Vendor ID is 'GenuineIntel'
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If you want to use libc, you must use the main

not entry point _start

. Make sure that you have installed gcc-multilib

, and just use gcc to compile and link: gcc -o cpuid2 cpuid2.s

. This should automatically do things right for you.



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