Linux-Bluetooth Archive on lore.kernel.org
 help / color / Atom feed
From: Shuah Khan <shuah@kernel.org>
To: marcel@holtmann.org, johan.hedberg@gmail.com, johan@kernel.org,
	viro@zeniv.linux.org.uk
Cc: Shuah Khan <shuah@kernel.org>,
	linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4] bluetooth: Fix WARNING in tty_set_termios()
Date: Sun,  3 Feb 2019 12:38:48 -0700
Message-ID: <20190203193848.12959-1-shuah@kernel.org> (raw)

tty_set_termios() has the following WARN_ON which can be triggered with a
syscall to invoke TIOCSETD __NR_ioctl.

WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
                tty->driver->subtype == PTY_TYPE_MASTER);
Reference: https://syzkaller.appspot.com/bug?id=2410d22f1d8e5984217329dd0884b01d99e3e48d

"The problem started with commit 7721383f4199 ("Bluetooth: hci_uart: Support
operational speed during setup") which introduced a new way for how
tty_set_termios() could end up being called for a master pty."

Fix it by by preventing setting the HCI line discipline for PTYs in
hci_uart_tty_open().

Reported-by: syzbot+a950165cbb86bdd023a4@syzkaller.appspotmail.com
Cc: Johan Hovold <johan@kernel.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Shuah Khan <shuah@kernel.org>
---
 drivers/bluetooth/hci_ldisc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..c8faa4759cb7 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -475,9 +475,9 @@ 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
+	 * hole. In addition check if setting HCI line discipline is allowed.
 	 */
-	if (tty->ops->write == NULL)
+	if (tty->ops->write == NULL || tty->ops->set_termios == NULL)
 		return -EOPNOTSUPP;
 
 	hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL);
-- 
2.17.1


             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-03 19:38 Shuah Khan [this message]
2019-02-04  5:39 ` Marcel Holtmann
2019-02-04 18:44   ` shuah

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190203193848.12959-1-shuah@kernel.org \
    --to=shuah@kernel.org \
    --cc=johan.hedberg@gmail.com \
    --cc=johan@kernel.org \
    --cc=linux-bluetooth@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marcel@holtmann.org \
    --cc=viro@zeniv.linux.org.uk \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Bluetooth Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-bluetooth/0 linux-bluetooth/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-bluetooth linux-bluetooth/ https://lore.kernel.org/linux-bluetooth \
		linux-bluetooth@vger.kernel.org linux-bluetooth@archiver.kernel.org
	public-inbox-index linux-bluetooth


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-bluetooth


AGPL code for this site: git clone https://public-inbox.org/ public-inbox