Re: [PATCH] cxl/hdm: Avoid NULL deref when component registers are missing

[Dan Williams <dan.j.williams@intel.com>]

Jonathan Cameron wrote:
> On Wed, 29 Mar 2023 14:35:43 -0700
> Dan Williams <dan.j.williams@intel.com> wrote:
> 
> > The cxl_port driver attempts to support endpoint devices that do not
> > advertise a component register block, but by inspection
> > devm_cxl_setup_hdm() passes a NULL @crb to helper functions that should
> > be skipped.
> > 
> > Return early and skip setting target_count since that is only relevant
> > for switch decoders, not endpoint decoders.
> 
> This is a good observation. It would be nice to not read it for the
> HDM decoder path either. Obviously we don't use it so that doesn't do
> any harm, but to someone reading the code it looks like we care about the
> value.  I'm not immediately sure how we'd establish at this layer that
> the HDM decoder is a switch or HB one though..

@info is NULL when this routine is called for non-endpoint decoders.

> > Fixes: 757f6448b100 ("cxl/hdm: Fix double allocation of @cxlhdm")
> > Tested-by: Dave Jiang <dave.jiang@intel.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> Patch looks fine to me.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>