linux-kernel - [PATCH v3] ssb: Fix potential NULL pointer dereference in ssb_device

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Date: Wed,  6 Mar 2024 15:30:28 +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: kvalo@...nel.org,
	deeb.rand@...fident.ru,
	lvc-project@...uxtesting.org,
	voskresenski.stanislav@...fident.ru,
	khoroshilov@...ras.ru,
	Rand Deeb <rand.sec96@...il.com>
Subject: [PATCH v3] 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 b9934b9c2d70..070a99a4180c 100644
--- a/drivers/ssb/main.c
+++ b/drivers/ssb/main.c
@@ -341,11 +341,13 @@ static int ssb_bus_match(struct device *dev, struct device_driver *drv)
 
 static int ssb_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
 {
-	const struct ssb_device *ssb_dev = dev_to_ssb_dev(dev);
+	const 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