Subject: Re: Coverity: console_prepend_dropped(): Memory - corruptions

From: John Ogness <[email-masked]>
Date: Tue, 17 Jan 2023 08:16:48 +0106

On 2023-01-17, Sergey Senozhatsky <[email-masked]> wrote:
> On (23/01/16 17:35), Petr Mladek wrote:
>> 	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?

Sure. But @0len is supposed to contain the number of bytes in
@scratchbuf, which theoretically it does not. snprintf() is the wrong
function to use here, even if there is not real danger in this
situation.

John Ogness