Debugging Dynamic Memory Usage Errors Using HP WDB (5900-1474; WDB 6.2; January 2011)

Example 11 Monitoring heap-corruption caused by erroneous handling of string functions

Sample Program

bash-2.05b$ cat string.c

1 #include<stdio.h>

3 int main()

4 {

5 char *ptr, *ptr1;

7 ptr = (char*)malloc(10);

8 ptr1 = (char *)malloc(20);

10 strcpy(ptr, "Hello");

11 strcpy(ptr1, "Welcome to HP WDB");

13 memcpy(ptr+5,ptr1,10);

14 }

Sample Debugging Session

bash-2.05b$ /opt/langtools/bin/gdb string

HP gdb 5.5.0 for PA-RISC 1.1 or 2.0 (narrow), HP-UX 11.00

and target hppa1.1-hp-hpux11.00.

Hewlett-Packard Wildebeest 5.5.0 (based on GDB) is

covered by the GNU General Public License.

Type "show copying" to see the conditions to

change it and/or distribute copies.

Type "show warranty" for warranty/support.

(gdb) set heap-check on

(gdb) set heap-check string on

(gdb) b main

Breakpoint 1 at 0x2bdc: file string.c, line 7 from string.

(gdb) r

Starting program: string

Breakpoint 1, main () at string.c:7

7 ptr = (char*)malloc(10);

(gdb) c

Continuing.

warning: memcpy corrupted (address = 0x4042a3dd size = 10)

#1 main() at string.c:7

#2 _start() from /usr/lib/libc.2

#3 _start() from /opt/langtools/lib/librtc.sl

#4 $START$() from

warning: Use command backtrace (bt) to see the current context.

Ignore top 4 frames belonging to leak detection library of gdb.

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

(gdb) bt

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

#1 0x70e7cc44 in search_addr+0x64 () from /opt/langtools/lib/librtc.sl

#2 0x70e7cd88 in libc_mem_common+0x130 () from /opt/langtools/lib/librtc.sl

Memory-Debugging Features of WDB 47