Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Why does this example C code run and yet SHOULD either not compile or give a segmentation fault?
Top Forums Programming Why does this example C code run and yet SHOULD either not compile or give a segmentation fault? Post 303033023 by wisecracker on Thursday 28th of March 2019 03:21:04 PM
Old 03-28-2019
Apologies if this attaches to the previous post.
As a finale to this thread I decided to compile using the correct 'asm()' function __asm__ volatile() .
Code:
/* Real obfuscation scenario. */

#include <stdio.h>

int addition(int NUM1, int NUM2);
int obfuscate(int NUM1, int NUM2);

int main()
{
    int NUMBER1;
    int NUMBER2;
    int SUM;

    __asm__ volatile("nop;"
    "jmp    out;"
    "in:"
    "nop;");

    printf("Enter two integer numbers:- ");
    scanf("%d %d", &NUMBER1, &NUMBER2);

    SUM = addition(NUMBER1, NUMBER2);

    printf("SUM = %d.\n", SUM);

    return(0);
}

int addition(int NUM1,int NUM2)
{
    int RESULT;
    RESULT = NUM1 + NUM2;
    return RESULT;
}

int obfuscate(int NUM1,int NUM2)
{
    int RESULT;

    __asm__ volatile("jmp    getout;"
    "nop;"
    "out:"
    "nop;"
    "jmp    in;"
    "getout:"
    "nop;");
    /* Any number of these jimps could be used to hide stuff. */

    RESULT = NUM1 / NUM2;
    return RESULT;
}

Results, OSX 10.14.3, default bash terminal, gcc 4.2.1.
The results are similar for AMIGA OS 3.0.x gcc 2.95.3 and Linunx Mint 19 gcc 7.3.0.
Code:
Last login: Thu Mar 28 18:58:36 on console
AMIGA:amiga~> cd Desktop/Code/C
AMIGA:amiga~/Desktop/Code/C> gcc -Wall -ansi obfuscate_asm.c -o obfuscate_asm
AMIGA:amiga~/Desktop/Code/C> ./obfuscate_asm
Enter two integer numbers:- 123 456
SUM = 579.
AMIGA:amiga~/Desktop/Code/C> hexdump -C obfuscate_asm
........
00000e90  55 48 89 e5 48 83 ec 20  c7 45 fc 00 00 00 00 90  |UH..H.. .E......|
00000ea0  e9 8b 00 00 00 90 48 8d  3d cb 00 00 00 b0 00 e8  |......H.=.......|
00000eb0  92 00 00 00 48 8d 3d da  00 00 00 48 8d 75 f8 48  |....H.=....H.u.H|
00000ec0  8d 55 f4 89 45 ec b0 00  e8 7f 00 00 00 8b 7d f8  |.U..E.........}.|
00000ed0  8b 75 f4 89 45 e8 e8 25  00 00 00 48 8d 3d b9 00  |.u..E..%...H.=..|
00000ee0  00 00 89 45 f0 8b 75 f0  b0 00 e8 57 00 00 00 31  |...E..u....W...1|
00000ef0  f6 89 45 e4 89 f0 48 83  c4 20 5d c3 0f 1f 40 00  |..E...H.. ]...@.|
00000f00  55 48 89 e5 89 7d fc 89  75 f8 8b 75 fc 03 75 f8  |UH...}..u..u..u.|
00000f10  89 75 f4 8b 45 f4 5d c3  0f 1f 84 00 00 00 00 00  |.u..E.].........|
00000f20  55 48 89 e5 89 7d fc 89  75 f8 e9 07 00 00 00 90  |UH...}..u.......|
00000f30  90 e9 6f ff ff ff 90 8b  45 fc 99 f7 7d f8 89 45  |..o.....E...}..E|
00000f40  f4 8b 45 f4 5d c3 ff 25  c4 00 00 00 ff 25 c6 00  |..E.]..%.....%..|
00000f50  00 00 00 00 4c 8d 1d ad  00 00 00 41 53 ff 25 9d  |....L......AS.%.|
00000f60  00 00 00 90 68 00 00 00  00 e9 e6 ff ff ff 68 0e  |....h.........h.|
00000f70  00 00 00 e9 dc ff ff ff  45 6e 74 65 72 20 74 77  |........Enter tw|
00000f80  6f 20 69 6e 74 65 67 65  72 20 6e 75 6d 62 65 72  |o integer number|
00000f90  73 3a 2d 20 00 25 64 20  25 64 00 53 55 4d 20 3d  |s:- .%d %d.SUM =|
00000fa0  20 25 64 2e 0a 00 00 00  01 00 00 00 1c 00 00 00  | %d.............|
........
AMIGA:amiga~/Desktop/Code/C> _

Voila! No error but the jumps are still there.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Segmentation Fault

hello all, I tried a program on an array to intialise array elements from the standard input device.it is an integer array of 5 elements.but after entering the 4th element it throws a message called "Segmentation Fault" and returns to the command prompt without asking for the 5th element. ... (3 Replies)
Discussion started by: compbug
3 Replies

2. AIX

Segmentation fault in nsgetcinfo in aix 64-bit c code

Hello, I am running on a AIX5.2 server with Oracle 10g and 9i. My code compiles and works fine in 32-bit mode. The same code compiles in 64-bit and runs good. The program catches CNTRL-C signal to terminate. Only on 64-bit code when i hit CNTRL-C, the program exits with segmentation... (0 Replies)
Discussion started by: sumesh0710
0 Replies

3. UNIX for Dummies Questions & Answers

Compile & Run Java Code

The java program is a part of speech tagger -> The Stanford NLP (Natural Language Processing) Group The goal is to use this script as part of a webpage to tag parts of speech based on a user-inputted string. I have no idea what to do with the files - I'm a complete *nix noob. I tried running... (4 Replies)
Discussion started by: tguillea
4 Replies

4. Programming

Segmentation fault.

I'm getting a segmentation fault. I'm new to Linux programming. Thanks so much for all of your input.:eek: #include </usr/include/mysql++/mysql++.h> #include <stdio.h> #include <iostream> #include <sstream> #include <string.h> using namespace std; int outputToImport(const char*... (1 Reply)
Discussion started by: sepoto
1 Replies

5. Programming

C code : Segmentation fault

Hi Friends, I have written a small code in C which performs the below operations Task : 1 ) read line by line from a file. 2 ) assuming 3th and 4th fields of the file as GN and GNTO 3 ) The target file should contain all the fields except GNTO. 4... (3 Replies)
Discussion started by: kiran_bhatter
3 Replies

6. UNIX for Advanced & Expert Users

segmentation fault with ps

What does this mean and why is this happening? $ ps -ef | grep ocular Segmentation fault (core dumped) $ ps -ef | grep ocular Segmentation fault (core dumped) $ ps aux | grep ocular Segmentation fault (core dumped) $ ps Segmentation fault (core dumped) $ pkill okular $ ps... (1 Reply)
Discussion started by: cokedude
1 Replies

7. Programming

Using gdb, ignore beginning segmentation fault until reproduce environment segmentation fault

I use a binary name (ie polo) it gets some parameter , so for debugging normally i do this : i wrote script for watchdog my app (polo) and check every second if it's not running then start it , the problem is , if my app , remain in state of segmentation fault for a while (ie 15 ... (6 Replies)
Discussion started by: pooyair
6 Replies

8. Programming

This code keeps giving me a segmentation fault why?

#include<stdlib.h> #include <pthread.h> #include "tlpi_hdr.h" #include <stdio.h> static volatile int glob = 0; static struct { pthread_t t1,t2; } *thread; static void * /* Loop 'arg' times incrementing 'glob' */ threadFunc(void *arg) { int loops = *((int *) arg); ... (1 Reply)
Discussion started by: fwrlfo
1 Replies

9. Solaris

Segmentation fault

Hi Guys, I just installed and booted a zone called testzone. When I logged in remotely and tried changing to root user I get this error: "Segmentation fault" Can someone please help me resolve this? Thanks alot (2 Replies)
Discussion started by: cjashu
2 Replies

10. Programming

C. To segmentation fault or not to segmentation fault, that is the question.

Oddities with gcc, 2.95.3 for the AMIGA and 4.2.1 for MY current OSX 10.14.1... I am creating a basic calculator for the AMIGA ADE *NIX emulator in C as it does not have one. Below are two very condensed snippets of which I have added the results inside the each code section. IMPORTANT!... (11 Replies)
Discussion started by: wisecracker
11 Replies

LEARN ABOUT OPENSOLARIS

mlib_signalconv_f32s_f32s

mlib_SignalConv_S16_S16_Sat(3MLIB)			    mediaLib Library Functions				mlib_SignalConv_S16_S16_Sat(3MLIB)

NAME

       mlib_SignalConv_S16_S16_Sat, mlib_SignalConv_S16S_S16S_Sat, mlib_SignalConv_F32_F32, mlib_SignalConv_F32S_F32S - signal convolution

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_SignalConv_S16_S16_Sat(mlib_s16 *dst,
	    const mlib_s16 *src1, const mlib_s16 *src2, mlib_s32 m,
	    mlib_s32 n);

       mlib_status mlib_SignalConv_S16S_S16S_Sat(mlib_s16 *dst,
	    const mlib_s16 *src1, const mlib_s16 *src2, mlib_s32 m,
	    mlib_s32 n);

       mlib_status mlib_SignalConv_F32_F32(mlib_f32 *dst,
	    const mlib_f32 *src1, const mlib_f32 *src2, mlib_s32 m,
	    mlib_s32 n);

       mlib_status mlib_SignalConv_F32S_F32S(mlib_f32 *dst,
	    const mlib_f32 *src1, const mlib_f32 *src2, mlib_s32 m,
	    mlib_s32 n);

DESCRIPTION

       Each of these functions performs convolution.

       For monaural signals, the following equation is used:

		  m-1
	 dst[i] = SUM (src1[j] * src2[i - j])  if m <= n
		  j=0

		  n-1
	 dst[i] = SUM (src2[j] * src1[i - j])  if m > n
		  j=0

       where i = 0, 1, ..., (m + n - 2).

       For stereo signals, the following equation is used:

			m-1
	 dst[2*i]     = SUM (src1[2*j] * src2[2*(i - j)])
			j=0

			m-1
	 dst[2*i + 1] = SUM (src1[2*j + 1] * src2[2*(i - j) + 1])
			j=0

       if m <= n, or

			n-1
	 dst[2*i]     = SUM (src2[2*j] * src1[2*(i - j)])
			j=0

			n-1
	 dst[2*i + 1] = SUM (src2[2*j + 1] * src1[2*(i - j) + 1])
			j=0

       if m > n; where i = 0, 1, ..., (m + n - 2).

PARAMETERS

       Each of the functions takes the following arguments:

       dst     Destination signal array.

       src1    First source signal array.

       src2    Second source signal array.

       m       Number of samples in the first source signal array.

       n       Number of samples in the second source signal arrays.

RETURN VALUES

       Each of the functions returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5)

SunOS 5.11							    2 Mar 2007					mlib_SignalConv_S16_S16_Sat(3MLIB)
All times are GMT -4. The time now is 01:37 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy