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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, Johan Hovold <johan@kernel.org>
Subject: [PATCH 5.14 030/162] misc: bcm-vk: fix tty registration race
Date:   Mon, 27 Sep 2021 19:01:16 +0200
Message-Id: <20210927170234.513156293@linuxfoundation.org>
In-Reply-To: <20210927170233.453060397@linuxfoundation.org>
References: <20210927170233.453060397@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit d9d1232b48344c6c72dbdf89fae1e7638e5df757 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: 91ca10d6fa07 ("misc: bcm-vk: add ttyVK support")
Cc: stable@vger.kernel.org      # 5.12
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917115736.5816-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/misc/bcm-vk/bcm_vk_tty.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/misc/bcm-vk/bcm_vk_tty.c
+++ b/drivers/misc/bcm-vk/bcm_vk_tty.c
@@ -267,13 +267,13 @@ int bcm_vk_tty_init(struct bcm_vk *vk, c
 		struct device *tty_dev;
 
 		tty_port_init(&vk->tty[i].port);
-		tty_dev = tty_port_register_device(&vk->tty[i].port, tty_drv,
-						   i, dev);
+		tty_dev = tty_port_register_device_attr(&vk->tty[i].port,
+							tty_drv, i, dev, vk,
+							NULL);
 		if (IS_ERR(tty_dev)) {
 			err = PTR_ERR(tty_dev);
 			goto unwind;
 		}
-		dev_set_drvdata(tty_dev, vk);
 		vk->tty[i].is_opened = false;
 	}