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References: <000000000000109f9605964acf6c@google.com> <20191101204244.14509-1-tomasbortoli@gmail.com>
 <E16896E5-B946-450F-BF42-04665D219EEA@holtmann.org>
In-Reply-To: <E16896E5-B946-450F-BF42-04665D219EEA@holtmann.org>
From:   Alexander Potapenko <glider@google.com>
Date:   Mon, 25 Nov 2019 13:40:51 +0100
Message-ID: <CAG_fn=Xqb1KoAvV==F5sODUYHDsxCxaz72n6qucdkR70XGCkig@mail.gmail.com>
Subject: Re: [PATCH] Fix invalid-free in bcsp_close()
To:     Marcel Holtmann <marcel@holtmann.org>,
        Tomas Bortoli <tomasbortoli@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        Bluez mailing list <linux-bluetooth@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        syzkaller <syzkaller@googlegroups.com>,
        syzbot+a0d209a4676664613e76@syzkaller.appspotmail.com
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Hi Tomas, Marcel, Greg,

On Mon, Nov 4, 2019 at 3:20 PM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Tomas,
>
> > Syzbot reported an invalid-free that I introduced fixing a memleak.
> >
> > bcsp_recv() also frees bcsp->rx_skb but never nullifies its value.
> > Nullify bcsp->rx_skb every time it is freed.
> >
> > Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> > Reported-by: syzbot+a0d209a4676664613e76@syzkaller.appspotmail.com
> > ---
> > drivers/bluetooth/hci_bcsp.c | 3 +++
> > 1 file changed, 3 insertions(+)
>
> patch has been applied to bluetooth-next tree.
I believe this bug requires stable tags, as it can potentially provide
an arbitrary write (via __skb_unlink) and is triggerable locally with
user privileges.
> Regards
>
> Marcel
>
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