linux-kernel - Re: [RFC][PATCH] vsprintf: Do not have bprintf dereference pointers

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Message-ID: <20171228200328.57b6c2fa@gandalf.local.home>
Date:   Thu, 28 Dec 2017 20:03:28 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [RFC][PATCH] vsprintf: Do not have bprintf dereference pointers

On Thu, 28 Dec 2017 18:50:26 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> +			default:
> +				if (!isalnum(*fmt)) {
> +					process = true;
> +					break;
> +				}
> +				/* Pointer dereference was already processed */
> +				if (str < end) {
> +					len = copy = strlen(args);
> +					if (copy > end - str)
> +						copy = end - str;
> +					memcpy(str, args, copy);
> +					str += copy;

Actually, that should have been: str += len; as str will be used to
return the amount that would be processed, even if the size wasn't long
enough.

V2 coming up.

-- Steve

> +					args += len;
> +				}
> +			}