Edit Question - KnowledgeHub

Title Body

I'm writing a program that loads and executes code from file. But i got a problem: "write" syscall does not work. Code successfully loads and executes, but does not display any text on the screen. Program that loads code: #include < stdio.h > #include < stdlib.h > int main(int argc,char* argv[]) { unsigned int f_size = 0; unsigned char* code_buf = NULL; void (*func_call)(void) = NULL; if(argc < 2) { printf("Usage: %s <FILE>\n",argv[0]); return 1; } FILE* fp = fopen(argv[1],"rb"); if(!fp) { printf("Error while opening this file: %s\n",argv[1]); return 1; } unsigned int fsize = 0; fseek(fp,0,SEEK_END); fsize = ftell(fp); fseek(fp,0,SEEK_SET); if(fsize < 4) { printf("Code size must be > 4 bytes\n"); return 1; } code_buf = (unsigned char*) malloc(sizeof(unsigned char)*fsize); if(fread(code_buf,fsize,1,fp)<1) { printf("Error while reading file: %s\n",argv[1]); free(code_buf); return 1; } func_call = (void (*)(void)) code_buf; printf("[EXEC] Binary is loaded\n" "\tFirst 2 bytes: 0x%x 0x%x\n" "\tLast 2 bytes: 0x%x 0x%x\n", code_buf[0],code_buf[1], code_buf[fsize-2],code_buf[fsize-1]); printf("[EXEC] Starting code...\n"); (*func_call)(); printf("[EXEC] Code executed!\n"); free(code_buf); return 0; } code that i trying to execute by this program (test.s): .text movl $4, %eax movl $1, %ebx movl $str, %ecx movl $5, %edx int $0x80 jmp end str: .string "test\n" end: ret Here is how i compile it: gcc -c test.s objcopy -O binary test.o test.bin Solved , thanks to @Christoph There are working code: .text

Tags (comma-separated) Cancel