linux-hardening - Re: [PATCH] printk: Use scnprintf() to print the message about the dropped messages on a console

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Date:   Wed, 18 Jan 2023 10:31:16 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        coverity-bot <keescook@...omium.org>,
        "Gustavo A . R . Silva" <gustavo@...eddedor.com>,
        linux-next@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        coverity-bot <keescook+coverity-bot@...omium.org>
Subject: Re: [PATCH] printk: Use scnprintf() to print the message about the
 dropped messages on a console

On Tue 2023-01-17 17:10:31, Petr Mladek wrote:
> Use scnprintf() for printing the message about dropped messages on
> a console. It returns the really written length of the message.
> It prevents potential buffer overflow when the returned length is
> later used to copy the buffer content.
> 
> Note that the previous code was safe because the scratch buffer was
> big enough and the message always fit in. But scnprintf() makes
> it more safe, definitely.
> 
> Reported-by: coverity-bot <keescook+coverity-bot@...omium.org>
> Addresses-Coverity-ID: 1530570 ("Memory - corruptions")
> Fixes: c4fcc617e148 ("printk: introduce console_prepend_dropped() for dropped messages")
> Link: https://lore.kernel.org/r/202301131544.D9E804CCD@keescook
> Signed-off-by: Petr Mladek <pmladek@...e.com>

JFYI, the patch has been comitted into printk/linux.git,
branch rework/buffers-cleanup.

Best Regards,
Petr