From: Marcel Holtmann <marcel@holtmann.org>
To: Vladis Dronov <vdronov@redhat.com>
Cc: Johan Hedberg <johan.hedberg@gmail.com>,
linux-bluetooth <linux-bluetooth@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Suraj Sumangala <suraj@atheros.com>,
Frederic Danis <frederic.danis@linux.intel.com>,
Loic Poulain <loic.poulain@intel.com>,
Balakrishna Godavarthi <bgodavar@codeaurora.org>,
syzkaller@googlegroups.com
Subject: Re: [PATCH v2] Bluetooth: hci_ldisc: check for missing tty operations
Date: Fri, 26 Jul 2019 23:48:02 +0200 [thread overview]
Message-ID: <62A82405-46E2-4921-BA52-D1660FC2DDDB@holtmann.org> (raw)
In-Reply-To: <20190726142628.20534-1-vdronov@redhat.com>
Hi Vladis,
> Certain ttys operations (pty_unix98_ops) lack tiocmget() and tiocmset()
> functions which are called by the certain HCI UART protocols (hci_ath,
> hci_bcm, hci_intel, hci_mrvl, hci_qca) via hci_uart_set_flow_control()
> or directly. This leads to an execution at NULL and can be triggered by
> an unprivileged user. Fix this by adding a check for the missing tty
> operations the same way it is done for write().
>
> This fixes CVE-2019-10207. The Fixes: lines list commits where calls to
> tiocm[gs]et() or hci_uart_set_flow_control() were added to the HCI UART
> protocols.
>
> Link: https://syzkaller.appspot.com/bug?id=1b42faa2848963564a5b1b7f8c837ea7b55ffa50
> Reported-by: syzbot+79337b501d6aa974d0f6@syzkaller.appspotmail.com
> Cc: stable@vger.kernel.org # v2.6.36+
> Fixes: c19483cc5e56 ("bluetooth: Fix missing NULL check")
> Fixes: b3190df62861 ("Bluetooth: Support for Atheros AR300x serial chip")
> Fixes: 118612fb9165 ("Bluetooth: hci_bcm: Add suspend/resume PM functions")
> Fixes: ff2895592f0f ("Bluetooth: hci_intel: Add Intel baudrate configuration support")
> Fixes: 162f812f23ba ("Bluetooth: hci_uart: Add Marvell support")
> Fixes: fa9ad876b8e0 ("Bluetooth: hci_qca: Add support for Qualcomm Bluetooth chip wcn3990")
> Signed-off-by: Vladis Dronov <vdronov@redhat.com>
> ---
>
> out-of-commit-message-note:
>
> I believe, this is a good location for the check. This way we protect protocols
> which does not call tiocm[gs]et() or hci_uart_set_flow_control() but may
> change to call them in the future.
>
> Also we do not need hci_uart_has_tiocm_support() helper now.
>
> drivers/bluetooth/hci_ldisc.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> index c84f985f348d..4a85c51d0307 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -459,10 +459,11 @@ static int hci_uart_tty_open(struct tty_struct *tty)
>
> BT_DBG("tty %p", tty);
>
> - /* Error if the tty has no write op instead of leaving an exploitable
> - * hole
> + /* Error if the tty has no write or tiocm[gs]et ops instead of leaving
> + * an exploitable hole
> */
> - if (tty->ops->write == NULL)
> + if (tty->ops->write == NULL || tty->ops->tiocmget == NULL ||
> + tty->ops->tiocmset == NULL)
> return -EOPNOTSUPP;
this means that you can not run hci_h4.c on any TTY anymore. For all the vendor specific ones, I agree, but H:4 is a Bluetooth SIG defined standard one that we might want to allow on any kind of TTY since it doesn’t really mandate anything.
So I would prefer if we go with a hci_uart_has_tiocm_support helper for now.
Regards
Marcel
next prev parent reply other threads:[~2019-07-26 21:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 14:26 [PATCH v2] Bluetooth: hci_ldisc: check for missing tty operations Vladis Dronov
2019-07-26 21:48 ` Marcel Holtmann [this message]
2019-07-29 12:22 ` [PATCH v3] Bluetooth: hci_uart: " Vladis Dronov
2019-07-30 9:34 ` Marcel Holtmann
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