linux-kernel - [PATCH 1/2] cxl/region: Fix potential invalid pointer dereference

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Date: Mon, 29 Apr 2024 09:31:53 +0800
From: Li Zhijian <lizhijian@...itsu.com>
To: dave@...olabs.net,
	jonathan.cameron@...wei.com,
	dave.jiang@...el.com,
	alison.schofield@...el.com,
	vishal.l.verma@...el.com,
	ira.weiny@...el.com,
	dan.j.williams@...el.com,
	linux-cxl@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Li Zhijian <lizhijian@...itsu.com>
Subject: [PATCH 1/2] cxl/region: Fix potential invalid pointer dereference

construct_region() could return a PTR_ERR() which cannot be derefernced.
Moving the dereference behind the error checking to make sure the
pointer is valid.

Fixes: a32320b71f08 ("cxl/region: Add region autodiscovery")
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
 drivers/cxl/core/region.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 8535718a20f0..3c80aa263a65 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3086,10 +3086,9 @@ int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
 	mutex_lock(&cxlrd->range_lock);
 	region_dev = device_find_child(&cxlrd->cxlsd.cxld.dev, hpa,
 				       match_region_by_range);
-	if (!region_dev) {
+	if (!region_dev)
 		cxlr = construct_region(cxlrd, cxled);
-		region_dev = &cxlr->dev;
-	} else
+	else
 		cxlr = to_cxl_region(region_dev);
 	mutex_unlock(&cxlrd->range_lock);
 
@@ -3097,6 +3096,9 @@ int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
 	if (rc)
 		goto out;
 
+	if (!region_dev)
+		region_dev = &cxlr->dev;
+
 	attach_target(cxlr, cxled, -1, TASK_UNINTERRUPTIBLE);
 
 	down_read(&cxl_region_rwsem);
-- 
2.29.2