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Date: Mon, 6 Jan 2025 21:29:28 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Andrew Morton
 <akpm@linux-foundation.org>, Petr Mladek <pmladek@suse.com>, Andy
 Shevchenko <andriy.shevchenko@linux.intel.com>, Rasmus Villemoes
 <linux@rasmusvillemoes.dk>, Sergey Senozhatsky <senozhatsky@chromium.org>,
 Kees Cook <keescook@chromium.org>
Subject: Re: [RFC][PATCH] printf: Harden accessing pointer dereference in
 vsprintf()
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On Mon, 6 Jan 2025 15:29:01 -0800
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, 6 Jan 2025 at 14:25, Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > Linus had suggested adding this kind of check[1]. This is a bit different
> > than Linus's solution as it utilizes copy_from_kernel_nofault() and doesn't
> > require calls to pagefault_disable() and extra labels.  
> 
> Yeah, and it generates horrendous code as a result.
> 

I guess the question is do we prefer horrendous code generated or what we see?

vsprintf() is used in critical paths, but I wonder how much these two
versions actually make a difference in performance? If they do, then yeah,
the open coded version would be better.

-- Steve