what will happen if we dereference the null pointer in user space and kernel space?
From my understanding the behaviour is based on compiler,architecture,etc.
but in general for every user space program allocated with virtual memory and the paging is used to translate the virtual address to physical address using page tables.
so if we are dereferencing null pointer in user space,that address is invalid so the context switch will happen and in kernel based on the interrupt for this null pointer dereference 'Segmentation fault will come or page fault error will come'.
In Kernel space:
If we dereference the NULL pointer there is a possibility of crashing the system or kernel may not able to return from that call.
Is my understanding correct?or any other informations missing means please explain.
Ref:I have understood from this "What happens in OS when we dereference a NULL pointer in C?"
The kernel maps the page at virtual address 0 into all processes with no permission bits set. When you try to access that page, you get a page fault. The kernel routine that handles it issues a SIGSEGV signal to your process. If you have no handler for SIGSEGV registered, core is dumped and you see your "Segmentation fault" message.
Kernel side, things are a bit different. After all, the kernel is supposed to be robust: