Date:   Tue, 7 Mar 2023 10:38:54 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Dongliang Mu <dzm91@hust.edu.cn>
Cc:     Alexander Aring <alex.aring@gmail.com>,
        Stefan Schmidt <stefan@datenfreihafen.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        syzbot+bd85b31816913a32e473@syzkaller.appspotmail.com,
        linux-wpan@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] net: ieee802154: fix a null pointer in
 nl802154_trigger_scan
Message-ID: <20230307103854.6536ad12@xps-13>
In-Reply-To: <20230307090546.994258-1-dzm91@hust.edu.cn>
References: <20230307090546.994258-1-dzm91@hust.edu.cn>
Organization: Bootlin
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Dongliang,

dzm91@hust.edu.cn wrote on Tue,  7 Mar 2023 17:05:46 +0800:

> There is a null pointer dereference if NL802154_ATTR_SCAN_TYPE is
> not set by the user.
>=20
> Fix this by adding a null pointer check.
>=20
> Reported-and-tested-by: syzbot+bd85b31816913a32e473@syzkaller.appspotmail=
.com

Still wrong :)

> 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(-)
>=20
> 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 *sk=
b, struct genl_info *info)
>  		return -EOPNOTSUPP;
>  	}
> =20
> -	if (!nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {
> +	if (!info->attrs[NL802154_ATTR_SCAN_TYPE] ||

Already handled :)

> +	    !nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {

Also handled!

>  		NL_SET_ERR_MSG(info->extack, "Malformed request, missing scan type");
>  		return -EINVAL;
>  	}


Thanks,
Miqu=C3=A8l