linux-kernel - Re: [PATCH next] Bluetooth: L2CAP: Fix NULL dereference in l2cap_recv

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Message-ID: <189055ae-a400-46b3-b265-a93a23f0d715@stanley.mountain>
Date: Thu, 13 Feb 2025 08:21:23 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
	Marcel Holtmann <marcel@...tmann.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH next] Bluetooth: L2CAP: Fix NULL dereference in
 l2cap_recv_acldata()

On Wed, Feb 12, 2025 at 05:23:42PM -0500, Luiz Augusto von Dentz wrote:
> Hi Dan,
> 
> On Wed, Feb 12, 2025 at 11:40 AM Dan Carpenter <dan.carpenter@...aro.org> wrote:
> >
> > The "conn" pointer is NULL so this "goto drop;" will lead to a NULL
> > dereference when we call mutex_unlock(&conn->lock). Free the skb and
> > return directly instead.
> >
> > Fixes: dd6367916d2d ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> >  net/bluetooth/l2cap_core.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 6cdc1dc3a7f9..fec11e576f31 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -7456,8 +7456,10 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
> >
> >         hci_dev_unlock(hcon->hdev);
> >
> > -       if (!conn)
> > -               goto drop;
> > +       if (!conn) {
> > +               kfree_skb(skb);
> > +               return;
> > +       }
> >
> >         BT_DBG("conn %p len %u flags 0x%x", conn, skb->len, flags);
> >
> > --
> > 2.47.2
> 
> I went ahead and fixed this in place since it has not been sent to net
> yet, I did add your Signed-off-by though.

Thanks.

regards,
dan carpenter