linux-kernel - Re: [PATCH] net: bluetooth: Fix null pointer dereference in hci_event

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Date:   Thu, 1 Oct 2020 09:06:42 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Anmol Karn <anmol.karan123@...il.com>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        open list <linux-kernel@...r.kernel.org>,
        syzkaller-bugs@...glegroups.com,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        syzbot+0bef568258653cff272f@...kaller.appspotmail.com
Subject: Re: [PATCH] net: bluetooth: Fix null pointer dereference in
 hci_event_packet()

Hi Anmol,

> AMP_MGR is getting derefernced in hci_phy_link_complete_evt(), when called from hci_event_packet() and there is a possibility, that hcon->amp_mgr may not be found when accessing after initialization of hcon.
> 
> - net/bluetooth/hci_event.c:4945
> The bug seems to get triggered in this line:
> 
> bredr_hcon = hcon->amp_mgr->l2cap_conn->hcon;
> 
> Fix it by adding a NULL check for the hcon->amp_mgr before checking the ev-status.
> 
> Fixes: d5e911928bd8 ("Bluetooth: AMP: Process Physical Link Complete evt")
> Reported-and-tested-by: syzbot+0bef568258653cff272f@...kaller.appspotmail.com 
> Link: https://syzkaller.appspot.com/bug?extid=0bef568258653cff272f 
> Signed-off-by: Anmol Karn <anmol.karan123@...il.com>
> ---
> Change in v3:
>  - changed return o; to return; (Reported-by: kernel test robot <lkp@...el.com>
> )
> 
> net/bluetooth/hci_event.c | 5 +++++
> 1 file changed, 5 insertions(+)

patch has been applied to bluetooth-next tree.

Regards

Marcel