Subject: Re: [Linux-kernel-mentees] [PATCH] net: bluetooth: Fix null pointer dereference in hci_event_packet()

From: Anmol Karn <[email-masked]>
Date: Thu, 10 Sep 2020 20:28:31 +0530

On Thu, Sep 10, 2020 at 01:49:18PM +0300, Dan Carpenter wrote:
> On Thu, Sep 10, 2020 at 10:04:24AM +0530, Anmol Karn wrote:
> > Prevent hci_phy_link_complete_evt() from dereferencing 'hcon->amp_mgr'
> > as NULL. Fix it by adding pointer check for it.
> > 
> > Reported-and-tested-by: [email-masked]
> > Link: https://syzkaller.appspot.com/bug?extid=0bef568258653cff272f
> > Signed-off-by: Anmol Karn <[email-masked]>
> > ---
> >  net/bluetooth/hci_event.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index 4b7fc430793c..871e16804433 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -4936,6 +4936,11 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev,
> >  		return;
> >  	}
> >  
> > +	if (IS_ERR_OR_NULL(hcon->amp_mgr)) {
> 
> It can't be an error pointer.  Shouldn't we call hci_conn_del() on this
> path?  Try to find the Fixes tag to explain how this bug was introduced.
> 
> (Don't rush to send a v2.  The patch requires quite a bit more digging
> and detective work before it is ready).
> 
> > +		hci_dev_unlock(hdev);
> > +		return;
> > +	}
> > +
> >  	if (ev->status) {
> >  		hci_conn_del(hcon);
> >  		hci_dev_unlock(hdev);
> 
> regards,
> dan carpenter
> 

Sure sir, will  work on it, thanks for your review.

Anmol Karn