linux-kernel - [PATCH] ssb: Fix potential NULL pointer dereference in ssb_device

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Message-Id: <20240229093756.129324-1-rand.sec96@gmail.com>
Date: Thu, 29 Feb 2024 12:37:56 +0300
From: Rand Deeb <rand.sec96@...il.com>
To: Michael Buesch <m@...s.ch>,
	linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: deeb.rand@...fident.ru,
	lvc-project@...uxtesting.org,
	voskresenski.stanislav@...fident.ru,
	Rand Deeb <rand.sec96@...il.com>
Subject: [PATCH] ssb: Fix potential NULL pointer dereference in ssb_device_uevent

The ssb_device_uevent function first attempts to convert the 'dev' pointer
to 'struct ssb_device *'. However, it mistakenly dereferences 'dev' before
performing the NULL check, potentially leading to a NULL pointer
dereference if 'dev' is NULL.

To fix this issue, this patch moves the NULL check before dereferencing the
'dev' pointer, ensuring that the pointer is valid before attempting to use
it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Rand Deeb <rand.sec96@...il.com>
---
 drivers/ssb/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ssb/main.c b/drivers/ssb/main.c
index 9e54bc7eec66..74f549557a01 100644
--- a/drivers/ssb/main.c
+++ b/drivers/ssb/main.c
@@ -340,11 +340,13 @@ static int ssb_bus_match(struct device *dev, struct device_driver *drv)
 
 static int ssb_device_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
-	struct ssb_device *ssb_dev = dev_to_ssb_dev(dev);
+	struct ssb_device *ssb_dev;
 
 	if (!dev)
 		return -ENODEV;
 
+	ssb_dev = dev_to_ssb_dev(dev);
+
 	return add_uevent_var(env,
 			     "MODALIAS=ssb:v%04Xid%04Xrev%02X",
 			     ssb_dev->id.vendor, ssb_dev->id.coreid,
-- 
2.34.1