Messages in this thread | | | Date | Wed, 1 Feb 2023 07:57:29 -0800 | From | Davidlohr Bueso <> | Subject | Re: [PATCH] cxl/region: Fix null pointer dereference for resetting decoder |
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On Thu, 15 Dec 2022, Fan Ni wrote:
>Not all decoders have a reset callback. > >The CXL specification allows a host bridge with a single root port to >have no explicit HDM decoders. Currently the region driver assumes there >are none. As such the CXL core creates a special pass through decoder >instance without a commit/reset callback. > >Prior to this patch, the ->reset() callback was called unconditionally when >calling cxl_region_decode_reset. Thus a configuration with 1 Host Bridge, >1 Root Port, and one directly attached CXL type 3 device or multiple CXL >type 3 devices attached to downstream ports of a switch can cause a null >pointer dereference. > >Before the fix, a kernel crash was observed when we destroy the region, and >a pass through decoder is reset. > >The issue can be reproduced as below, > 1) create a region with a CXL setup which includes a HB with a > single root port under which a memdev is attached directly. > 2) destroy the region with cxl destroy-region regionX -f. > >Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware") >Signed-off-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
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