linux-hardening - Re: Coverity: console_prepend_dropped(): Memory

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Date:   Tue, 17 Jan 2023 12:07:50 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        coverity-bot <keescook@...omium.org>,
        John Ogness <john.ogness@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        linux-next@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: Coverity: console_prepend_dropped(): Memory - corruptions

On (23/01/16 17:35), Petr Mladek wrote:
> 
> I am going to send a patch.

Sure, sounds good.

> The code might be safe with the current size of the buffer and
> the string. But it is true that the following is wrong:
> 
> 	len = snprintf(scratchbuf, scratchbuf_sz,
> 		       "** %lu printk messages dropped **\n", dropped);

Wouldn't

	if (WARN_ON_ONCE(len + PRINTK_PREFIX_MAX >= outbuf_sz))
		return;

prevent us from doing something harmful?