Re: [PATCH v2 3/4] software node: verify that property data is not on stack

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Mon, Mar 30, 2026 at 01:33:47PM +0300, Andy Shevchenko wrote:
> On Sun, Mar 29, 2026 at 07:27:50PM -0700, Dmitry Torokhov wrote:
> > When registering a software node, ensure that the property data is not
> > located on the stack, as it is expected to persist for the lifetime of
> > the node.
> 
> ...
> 
> > +	for (prop = node->properties; prop && prop->name; prop++) {
> > +		if (!prop->is_inline && object_is_on_stack(prop->pointer)) {
> 
> I read more about this... Any code that uses vmalloc() (or potentially may
> switch to it from regular allocator with help of kvalloc() and similar) will
> fail now. While it might be no issue right now, this may become a such. So
> with this check in place you put a requirement that properties can only be
> allocated from a kernel low memory heap and not vm.

Can you tell me more about this? As far as I can see it will actually
have false negatives with CONFIG_VMAP_STACK, but should be OK not
trigger with vmalloced memory... But I am genuinely interested to know
more.

Thanks.

-- 
Dmitry