Questions tagged [libc]
C standard library for the C programming language as specified in the C specification (ANSI C, C99, C11, ...).
9
questions
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vote
0answers
59 views
How can a segfault happen during the libc exit call on Linux?
I'm relatively new to reverse engineering, and I've decided to practise using the challenges from pwnable.tw. Currently, I am working on the "Silver Bullet" challenge.
While testing, I have noticed ...
0
votes
1answer
224 views
How can I intercept syscall libc function in C++ without writing any code in C file
How can intercept libc function in C++ using LD_PRELOAD. I want to write code only in C++ file and all the logic of symbol fishing (dlsym) must be in C++ file.
Please give an example.
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2answers
54 views
`dmi libc puts~GLOBAL` does not show puts, just putspent?
On the tutorial by Megabeets, "A journey into Radare 2 – Part 2: Exploitation"
[0x080483d0]> dmi libc puts~&GLOBAL, puts:0
532 0x000fdd60 0xf7e0bd60 GLOBAL FUNC 1181 putspent
[0x080483d0]&...
1
vote
1answer
477 views
Found the adress of a function LIBC without GDB
How to calculate the address of a function in the LIBC, when ASLR is not active.
I only have the address where to load the LIBC (with ldd /bin/bash).
Thank you for the explanations
EDIT:
When I use ...
0
votes
1answer
64 views
Why is j_free function and free_ptr pointer needed in glibc?
I am disassembling libc-2.23.so, there exists a thunk method called j_free which jumps at the location pointed to by free_ptr pointer in glibc. Why do those even exist while free() itself is exported?
8
votes
2answers
5k views
How does glibc malloc work?
Wishing to dig in the internals of dynamic memory allocation on Linux, the best I could find is an article titled Understanding glibc malloc. The explanation, though detailed, is not quite ...
1
vote
2answers
1k views
Recognizing CLib functions in Ollydbg or IDA
I'm just learning Olly/IDA and writing simple programs in C and looking at the .EXE code in Ollydbg and IDA. Below I have a simple printf Hello World program which I compile in Visual Studio 6. I ...
3
votes
1answer
127 views
Exploitability of Stack-based Buffer Overflows on functions ending with fclose()
I have been discussing the effectiveness of GNU libc's fclose() function to thwart successful exploitation of trivial vulnerabilities due to segmentation fault when called without a valid pointer to a ...
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0answers
69 views
dlmalloc free pointers
I was looking at the implementation of "free" in my current dlmalloc(both the source and the disassembly). However, I could not find the code section the inserts the FD and BK into free chunks. What ...
