From:   Dongliang Mu <dzm91@hust.edu.cn>
To:     Alexander Aring <alex.aring@gmail.com>,
        Stefan Schmidt <stefan@datenfreihafen.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     Dongliang Mu <dzm91@hust.edu.cn>,
        syzbot+bd85b31816913a32e473@syzkaller.appspotmail.com,
        linux-wpan@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v2] net: ieee802154: fix a null pointer in nl802154_trigger_scan
Date:   Tue,  7 Mar 2023 17:05:46 +0800
Message-Id: <20230307090546.994258-1-dzm91@hust.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

There is a null pointer dereference if NL802154_ATTR_SCAN_TYPE is
not set by the user.

Fix this by adding a null pointer check.

Reported-and-tested-by: syzbot+bd85b31816913a32e473@syzkaller.appspotmail.com
Fixes: a0b6106672b5 ("ieee802154: Convert scan error messages to extack")
Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
---
v1->v2: add fixes tag
 net/ieee802154/nl802154.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
index 2215f576ee37..1cf00cffd63f 100644
--- a/net/ieee802154/nl802154.c
+++ b/net/ieee802154/nl802154.c
@@ -1412,7 +1412,8 @@ static int nl802154_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 		return -EOPNOTSUPP;
 	}
 
-	if (!nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {
+	if (!info->attrs[NL802154_ATTR_SCAN_TYPE] ||
+	    !nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {
 		NL_SET_ERR_MSG(info->extack, "Malformed request, missing scan type");
 		return -EINVAL;
 	}
-- 
2.34.1