Questions tagged [gcc]

GNU Compiler Collection, it includes front ends for C, C++, Objective-C, Fortran, Java, Ada, and Go, as well as libraries for these languages (libstdc++, libgcj,...).

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How can I tell ld to link to a local symbol in a shared object?

Symbols in shared objects can be either local or global. This is controlled by a flag in the symbol table. If the symbol is local, ld won't resolve to it. Reverse engineering can often be aided by ...
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92 views

Changing value of parameter with gdb

I have a file named exploit.c inside which: #include <stdbool.h> #include <stdio.h> const char y1 = 'a'; const char y2 = 'b'; const char y3 = 'x'; const char y4 = 'y'; const char y5 = 'i';...
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Is disassembly of standard gcc programs trivial, or just as difficult as video game ROMs?

I am attempting to do some reverse-engineering of ARM binaries, with the ultimate goal of reverse-engineering GBA ROMs. Of course, GBA ROMs contain a mixture of code and data, so a standard ...
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silvio packer for shared libray leads to error: "ELF load command address/offset not properly aligned"

I'm trying to implement a packer based on silvio infection. The packer works fine for ET_EXEC. However, it failed with "ELF load command address/offset not properly aligned" error for the ...
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failed to trigger packer's loader by overwritting the entry of rela.dyn on aarch64

I have implemented packer of x86_64 shared library. Briefly, a loader is injected to a shared library, and the rela.dyn entry is modified such that it points to the address of the loader. Once the ...
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735 views

How can I control local variable ordering on stack in gcc?

I am writing a reversing challenge where I need to seed a bug. It's important to have a particular ordering of local variable on stack in a method. However, gcc seems to shuffle those around. How can ...
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1answer
623 views

Problem to understand execution of payload (shellcode)

I know that there are lot of (good) tutorials regarding this topic, but after reading them, I really cant follow their thoughts (e.g.: Smashing The Stack For Fun And Profit): The problem is that we ...
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Radare2 is showing weird disassembly as compared to disassembly of gcc

Today i was playing around with c code in r2. I compiled a file which had the following code. #include <stdio.h> int main(){ int a=9; float b=1.1; int sum; sum = ...
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Force gcc to use more complex instructions

I am reverse engineering a piece of assembly. I am trying to write the equivalent code in C, however, when I compile my code, gcc prefers to use simple instructions instead of the complex ones that ...
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328 views

How to pass Obfuscated Elf binary to gcc optimization end

Currently I have a 2000+Line function to reverse engineer with many redundancies and appears to be obfuscated. It their a way to pass to pass this binary to gcc or clang to reassemble it and optimize ...