From: Kees Cook <kees@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.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>
Subject: Re: [RFC][PATCH] printf: Harden accessing pointer dereference in vsprintf()
Date: Mon, 6 Jan 2025 16:33:00 -0800 [thread overview]
Message-ID: <202501061632.76CF72FC@keescook> (raw)
In-Reply-To: <20250106172722.5b6032e5@gandalf.local.home>
On Mon, Jan 06, 2025 at 05:27:22PM -0500, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> For extra safety from crashing the kernel, add a
> copy_from_kernel_nofault() in check_pointer_msg(). If it fails to read the
> memory, then return "(efault)".
>
> This isn't full proof, as the length of the pointer being read could
> possibly go into bad memory, but this should catch the majority of errors.
>
> 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.
>
> [1] https://lore.kernel.org/all/CAHk-=wh3cUC2a=yJv42HTjDLCp6VM+GTky+q65vV_Q33BeoxAg@mail.gmail.com/
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Seems reasonable to me.
Reviewed-by: Kees Cook <kees@kernel.org>
-Kees
--
Kees Cook
next prev parent reply other threads:[~2025-01-07 0:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-06 22:27 [RFC][PATCH] printf: Harden accessing pointer dereference in vsprintf() Steven Rostedt
2025-01-06 23:29 ` Linus Torvalds
2025-01-07 2:29 ` Steven Rostedt
2025-01-07 3:05 ` Linus Torvalds
2025-01-07 0:33 ` Kees Cook [this message]
2025-01-07 4:33 ` Sergey Senozhatsky
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