linux-kernel - [PATCH v4 1/7] cxl/region: Avoid null pointer dereference in is_cxl

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Message-ID: <20250603221949.53272-2-Smita.KoralahalliChannabasappa@amd.com>
Date: Tue, 3 Jun 2025 22:19:43 +0000
From: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
To: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>,
	<linux-pm@...r.kernel.org>
CC: Davidlohr Bueso <dave@...olabs.net>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Matthew Wilcox <willy@...radead.org>, Jan Kara
	<jack@...e.cz>, "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown
	<len.brown@...el.com>, Pavel Machek <pavel@...nel.org>, Li Ming
	<ming.li@...omail.com>, Jeff Johnson <jeff.johnson@....qualcomm.com>, "Ying
 Huang" <huang.ying.caritas@...il.com>, Yao Xingtao <yaoxt.fnst@...itsu.com>,
	Peter Zijlstra <peterz@...radead.org>, Greg KH <gregkh@...uxfoundation.org>,
	Nathan Fontenot <nathan.fontenot@....com>, Smita Koralahalli
	<Smita.KoralahalliChannabasappa@....com>, Terry Bowman
	<terry.bowman@....com>, Robert Richter <rrichter@....com>, Benjamin Cheatham
	<benjamin.cheatham@....com>, PradeepVineshReddy Kodamati
	<PradeepVineshReddy.Kodamati@....com>, Zhijian Li <lizhijian@...itsu.com>
Subject: [PATCH v4 1/7] cxl/region: Avoid null pointer dereference in is_cxl_region()

Add a NULL check in is_cxl_region() to prevent potential null pointer
dereference if a caller passes a NULL device. This change ensures the
function safely returns false instead of triggering undefined behavior
when dev is NULL.

Co-developed-by: Nathan Fontenot <Nathan.Fontenot@....com>
Signed-off-by: Nathan Fontenot <Nathan.Fontenot@....com>
Co-developed-by: Terry Bowman <terry.bowman@....com>
Signed-off-by: Terry Bowman <terry.bowman@....com>
Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
---
 drivers/cxl/core/region.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index c3f4dc244df7..109b8a98c4c7 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2333,7 +2333,7 @@ const struct device_type cxl_region_type = {
 
 bool is_cxl_region(struct device *dev)
 {
-	return dev->type == &cxl_region_type;
+	return dev && dev->type == &cxl_region_type;
 }
 EXPORT_SYMBOL_NS_GPL(is_cxl_region, "CXL");
 
-- 
2.17.1