linux-kernel - Re: [PATCH] tty: ttynull: implement console write

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Date:   Tue, 14 Feb 2023 11:50:33 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Michael Thalmeier <michael.thalmeier@...e.at>
Cc:     Jiri Slaby <jirislaby@...nel.org>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: ttynull: implement console write

On Tue, Feb 14, 2023 at 11:23:17AM +0100, Michael Thalmeier wrote:
> Since commit 3579b59c7edc475013ae769a2d26d99733c95f13 ("printk: refactor

Nit, sha ids should only be 12 digits, as per the kernel documentation,
can you fix that up?

And wait, that's not even a commit id, are you sure that is correct?

> and rework printing logic"), con->write is called without checking if it
> is implemented in the console driver. This does make some sense, because
> for all "normal" consoles it is vital to have a write function.
> As the ttynull console driver does not need any console output the write
> function was not implemented. This caused a "unable to handle kernel NULL
> pointer dereference" when the write function is called now.
> 
> To fix this issue, implement an empty write function.
> 
> Signed-off-by: Michael Thalmeier <michael.thalmeier@...e.at>
> Cc: stable@...r.kernel.org

Adding a Fixes: tag here would also be good to have.

thanks,

greg k-h