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

From: Dan Williams <dan.j.williams@intel.com>
To: linux-cxl@vger.kernel.org
Cc: Dave Jiang <dave.jiang@intel.com>
Subject: [PATCH] cxl/hdm: Avoid NULL deref when component registers are missing
Date: Wed, 29 Mar 2023 14:35:43 -0700	[thread overview]
Message-ID: <168012574357.221280.5001364964799725366.stgit@dwillia2-xfh.jf.intel.com> (raw)

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.

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>
---
 drivers/cxl/core/hdm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 5293fe13fce3..cc123996b1a4 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -123,7 +123,7 @@ struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
 	crb = ioremap(port->component_reg_phys, CXL_COMPONENT_REG_BLOCK_SIZE);
 	if (!crb && info && info->mem_enabled) {
 		cxlhdm->decoder_count = info->ranges;
-		cxlhdm->target_count = info->ranges;
+		return cxlhdm;
 	} else if (!crb) {
 		dev_err(dev, "No component registers mapped\n");
 		return ERR_PTR(-ENXIO);

