From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
x86@kernel.org
Subject: Re: [PATCH] x86/uaccess: instrument copy_from_user_nmi()
Date: Thu, 27 Oct 2022 10:05:47 +0200 [thread overview]
Message-ID: <Y1o72704bVK0FgCr@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAG_fn=XDeghFBGXT37Mc-ky-8NaPaMmCLdo3Par=xh92Fk_CAQ@mail.gmail.com>
On Wed, Oct 26, 2022 at 11:38:53AM -0700, Alexander Potapenko wrote:
> A bigger issue from the NMI perspective is probably
> having __msan_poison_alloca() inserted in every non-noinstr kernel
> function, because that hook may acquire the stackdepot lock.
*urgghhh* that's broken, that must not be. There is a *TON* of NMI
functions that are non-noinstr.
What's worse, it seems to do a memory allocation as well, and that's out
the window with PREEMPT_RT where you can't do even GFP_ATOMIC from
regular IRQ context.
That function is wholly unacceptable to be added to every kernel
function.
next prev parent reply other threads:[~2022-10-27 8:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 22:17 [PATCH] x86/uaccess: instrument copy_from_user_nmi() Alexander Potapenko
2022-10-26 9:30 ` Peter Zijlstra
2022-10-26 18:38 ` Alexander Potapenko
2022-10-27 8:05 ` Peter Zijlstra [this message]
2022-10-27 18:26 ` Alexander Potapenko
2022-10-27 18:58 ` Kees Cook
2022-10-27 19:26 ` Peter Zijlstra
2022-10-27 23:24 ` Alexander Potapenko
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