Debugging Dynamic Memory Usage Errors Using HP WDB v6.3 (5900-2181, August 2012)

Example 21 Detecting de-allocation of un-allocated blocks

Sample Program

$ cat unit.c

1 #include<stdio.h>

3 int main() {

5 printf("Starting program\n");

6 int *han = (int*)malloc(sizeof(int));

7 han++;

8 free(han);

9 }

Sample Debugging Session

(gdb) set heap-check on

(gdb) file uninit

Reading symbols from uninit...done.

(gdb) b main

Breakpoint 1 at 0x2bdc: file uninit.c, line 5 from uninit.

(gdb) r

Starting program: uninit

Breakpoint 1, main () at uninit.c:5

5 printf("Starting program\n");

(gdb) n

Starting program

6 int *han = (int*)malloc(sizeof(int));

(gdb)

7 han++;

(gdb)

8 free(han);

(gdb)

warning: Attempt to free unallocated or already freed

object at 0x4042c3e4

0x70e78d7c in __rtc_event+0 () from /opt/langtools/lib/librtc.sl