Re: [PATCH v3 1/3] kprobes: Add text_alloc() and text_free()

[Kees Cook]

On Wed, Jul 15, 2020 at 05:27:32PM +0900, Masami Hiramatsu wrote:
> 
> On Wed, 15 Jul 2020 01:32:27 +0300
> Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> > [...]
> > -void *module_alloc(unsigned long size)
> > -{
> > -	void *p;
> > -
> > -	if (PAGE_ALIGN(size) > MODULES_LEN)
> > -		return NULL;
> > -
> > -	p = __vmalloc_node_range(size, MODULE_ALIGN,
> > -				    MODULES_VADDR + get_module_load_offset(),
> > -				    MODULES_END, GFP_KERNEL,
> > -				    PAGE_KERNEL, 0, NUMA_NO_NODE,
> > -				    __builtin_return_address(0));
> > -	if (p && (kasan_module_alloc(p, size) < 0)) {
> > -		vfree(p);
> > -		return NULL;
> > -	}
> > -
> > -	return p;
> > -}
> 
> Please don't touch this module_alloc() at all. Then we can
> just call __vmalloc_node_range() in the text_alloc().

Hm? I thought the requirement was that trampolines needed to stay within
a certain distance of kernel text and that the module_alloc() enforced
that?

-- 
Kees Cook