I’ve created a file which prints Hello, world as many times at the user wants to give input.
#include <stdio.h> #include <string.h> int main() { char message[10]; int count, i; strcpy(message, "Hello, world!"); printf("Repeat how many times? "); scanf("%d", &count); for(i=0; i < count; i++) printf("%3d - %s\n", i, message); }
No matter what the number entered it always results in a “stack smash”. Here is the program, can anyone come up with a conclusion to why it is doing this? Here is the “traceback” that occurs after the stack smash is detected:
sean@blue:~/programming$ ./a.out Repeat how many times? 12 0 - Hello, world! 1 - Hello, world! 2 - Hello, world! 3 - Hello, world! 4 - Hello, world! 5 - Hello, world! 6 - Hello, world! 7 - Hello, world! 8 - Hello, world! 9 - Hello, world! 10 - Hello, world! 11 - Hello, world! *** stack smashing detected ***: ./a.out terminated ======= Backtrace: ========= /lib/i386-linux-gnu/libc.so.6(__fortify_fail+0x45)[0x1f8c75] /lib/i386-linux-gnu/libc.so.6(+0xe8c27)[0x1f8c27] ./a.out[0x8048524] /lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0x129113] ./a.out[0x80483f1] ======= Memory map: ======== 00110000-00288000 r-xp 00000000 08:01 1577912 /lib/i386-linux-gnu/libc-2.13.so 00288000-0028a000 r--p 00178000 08:01 1577912 /lib/i386-linux-gnu/libc-2.13.so 0028a000-0028b000 rw-p 0017a000 08:01 1577912 /lib/i386-linux-gnu/libc-2.13.so 0028b000-0028e000 rw-p 00000000 00:00 0 0036b000-0036c000 r-xp 00000000 00:00 0 [vdso] 00454000-00470000 r-xp 00000000 08:01 1573818 /lib/i386-linux-gnu/libgcc_s.so.1 00470000-00471000 r--p 0001b000 08:01 1573818 /lib/i386-linux-gnu/libgcc_s.so.1 00471000-00472000 rw-p 0001c000 08:01 1573818 /lib/i386-linux-gnu/libgcc_s.so.1 00e7e000-00e9c000 r-xp 00000000 08:01 1573924 /lib/i386-linux-gnu/ld-2.13.so 00e9c000-00e9d000 r--p 0001d000 08:01 1573924 /lib/i386-linux-gnu/ld-2.13.so 00e9d000-00e9e000 rw-p 0001e000 08:01 1573924 /lib/i386-linux-gnu/ld-2.13.so 08048000-08049000 r-xp 00000000 00:14 3801591 /home/sean/programming/a.out 08049000-0804a000 r--p 00000000 00:14 3801591 /home/sean/programming/a.out