From: Jiri Slaby <jslaby@suse.cz>
To: Gen Zhang <blackgod016574@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty_io.c
Date: Wed, 22 May 2019 06:25:36 +0200 [thread overview]
Message-ID: <abc68141-df99-1ae1-ea51-c83bd4480d92@suse.cz> (raw)
In-Reply-To: <20190522014006.GB4093@zhanggen-UX430UQ>
On 22. 05. 19, 3:40, Gen Zhang wrote:
> In alloc_tty_struct(), tty->dev is assigned by tty_get_device(). And it
> calls class_find_device(). And class_find_device() may return NULL.
> And tty->dev is dereferenced in the following codes. When
> tty_get_device() returns NULL, dereferencing this tty->dev null pointer
> may cause the kernel go wrong. Thus we should check tty->dev.
> Further, if tty_get_device() returns NULL, we should free tty and
> return NULL.
>
> Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
>
> ---
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 033ac7e..1444b59 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -3008,6 +3008,10 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
> tty->index = idx;
> tty_line_name(driver, idx, tty->name);
> tty->dev = tty_get_device(tty);
> + if (!tty->dev) {
> + kfree(tty);
> + return NULL;
> + }
This is incorrect, you introduced an ldisc reference leak.
And can this happen at all?
thanks,
--
js
suse labs
next prev parent reply other threads:[~2019-05-22 4:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-22 1:40 [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty_io.c Gen Zhang
2019-05-22 4:25 ` Jiri Slaby [this message]
2019-05-22 8:06 ` Gen Zhang
2019-05-22 8:15 ` Jiri Slaby
2019-05-22 10:29 ` Johan Hovold
2019-05-22 10:32 ` Jiri Slaby
2019-05-22 11:13 ` Gen Zhang
2019-05-22 11:19 ` Johan Hovold
2019-05-22 11:24 ` Gen Zhang
2019-05-22 11:18 ` Gen Zhang
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