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@linaro.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

Hi Dan,

On Wed, Feb 12, 2025 at 11:40 AM Dan Carpenter <dan.carpenter@linaro.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@linaro.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.

-- 
Luiz Augusto von Dentz

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@linaro.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@linaro.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