linux-kernel - Re: [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty

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Message-ID: <20190522111354.GA5849@zhanggen-UX430UQ>
Date:   Wed, 22 May 2019 19:13:54 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     Johan Hovold <johan@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty_io: Fix a missing-check bug in drivers/tty/tty_io.c

On Wed, May 22, 2019 at 12:29:00PM +0200, Johan Hovold wrote:
> Where do you see that the kernel is dereferencing tty->dev without
> checking for NULL first? If you can find that, then that would indeed be
> a bug that needs fixing.
Thanks for your reply, Johan!
I examined the code but failed to find this situation.
Anyway, checking return value of tty_get_device() is theoritically
right. But tty->dev is never dereferenced, so checking is not needed.
However, what if in later kernels tty->dev is dereferenced by some
codes? Is it better to apply this check for this reason?
Thanks
Gen