[PATCH 6.1.y] ssb: Fix potential NULL pointer dereference in ssb_device_uevent()

[Imkanmod Khan <imkanmodkhan@gmail.com>]

From: Rand Deeb <rand.sec96@gmail.com>

[ Upstream commit 789c17185fb0f39560496c2beab9b57ce1d0cbe7 ]

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, move 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@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240306123028.164155-1-rand.sec96@gmail.com
Signed-off-by: Imkanmod Khan <imkanmodkhan@gmail.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 d52e91258e98..aae50a5dfb57 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(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,
-- 
2.25.1