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Subject: Re: [PATCH] Bluetooth: hci_ldisc: Initialize hci_dev before open()
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20190206175416.4627-1-jcline@redhat.com>
Date:   Mon, 18 Feb 2019 13:55:30 +0100
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzbot+257790c15bcdef6fe00c@syzkaller.appspotmail.com
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Message-Id: <37BAD6CD-1A0C-4DF2-95E0-2D75D7A75DB8@holtmann.org>
References: <20190206175416.4627-1-jcline@redhat.com>
To:     Jeremy Cline <jcline@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Jeremy,

> The hci_dev struct hdev is referenced in work queues and timers started
> by open() in some protocols. This creates a race between the
> initialization function and the work or timer which can result hdev
> being dereferenced while it is still null.
> 
> The syzbot report contains a reliable reproducer which causes a null
> pointer dereference of hdev in hci_uart_write_work() by making the
> memory allocation for hdev fail.
> 
> To fix this, ensure hdev is valid from before calling a protocol's
> open() until after calling a protocol's close().
> 
> Reported-by: syzbot+257790c15bcdef6fe00c@syzkaller.appspotmail.com
> Signed-off-by: Jeremy Cline <jcline@redhat.com>
> ---
> drivers/bluetooth/hci_ldisc.c | 21 ++++++++++++++-------
> 1 file changed, 14 insertions(+), 7 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel