If you have been experiencing segmentation fault issues with GDB while attaching to a process on a jailbroken iOS device, it is because the GDB that comes with Cydia is broken and you need to install a proper version. You can download a proper working version of GDB from here. You need to copy this executable into /usr/bin on your jailbroken iOS device and give it executable permissions. If it still doesn’t work, let me know what issue you are facing by writing a comment below.