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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Samuel Iglesias Gonsalvez <siglesias@igalia.com>,
        Johan Hovold <johan@kernel.org>
Subject: [PATCH 4.14 56/75] ipack: ipoctal: fix tty registration race
Date:   Mon,  4 Oct 2021 14:52:31 +0200
Message-Id: <20211004125033.410212330@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 65c001df517a7bf9be8621b53d43c89f426ce8d6 upstream.

Make sure to set the tty class-device driver data before registering the
tty to avoid having a racing open() dereference a NULL pointer.

Fixes: 9c1d784afc6f ("Staging: ipack/devices/ipoctal: Get rid of ipoctal_list.")
Cc: stable@vger.kernel.org      # 3.7
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917114622.5412-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/ipack/devices/ipoctal.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/ipack/devices/ipoctal.c
+++ b/drivers/ipack/devices/ipoctal.c
@@ -398,13 +398,13 @@ static int ipoctal_inst_slot(struct ipoc
 		spin_lock_init(&channel->lock);
 		channel->pointer_read = 0;
 		channel->pointer_write = 0;
-		tty_dev = tty_port_register_device(&channel->tty_port, tty, i, NULL);
+		tty_dev = tty_port_register_device_attr(&channel->tty_port, tty,
+							i, NULL, channel, NULL);
 		if (IS_ERR(tty_dev)) {
 			dev_err(&ipoctal->dev->dev, "Failed to register tty device.\n");
 			tty_port_destroy(&channel->tty_port);
 			continue;
 		}
-		dev_set_drvdata(tty_dev, channel);
 	}
 
 	/*