linux-kernel - [PATCH] rfkill: Fix incorrect check to avoid NULL pointer dereference

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Message-Id: <20191215153409.21696-1-pakki001@umn.edu>
Date:   Sun, 15 Dec 2019 09:34:08 -0600
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] rfkill: Fix incorrect check to avoid NULL pointer dereference

In rfkill_register, the struct rfkill pointer is first derefernced
and then checked for NULL. This patch removes the BUG_ON and returns
an error to the caller in case rfkill is NULL.

Signed-off-by: Aditya Pakki <pakki001@....edu>
---
 net/rfkill/core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/rfkill/core.c b/net/rfkill/core.c
index 461d75274fb3..971c73c7d34c 100644
--- a/net/rfkill/core.c
+++ b/net/rfkill/core.c
@@ -1002,10 +1002,13 @@ static void rfkill_sync_work(struct work_struct *work)
 int __must_check rfkill_register(struct rfkill *rfkill)
 {
 	static unsigned long rfkill_no;
-	struct device *dev = &rfkill->dev;
+	struct device *dev;
 	int error;
 
-	BUG_ON(!rfkill);
+	if (!rfkill)
+		return -EINVAL;
+
+	dev = &rfkill->dev;
 
 	mutex_lock(&rfkill_global_mutex);
 
-- 
2.20.1