From: Kees Cook <keescook@chromium.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Uladzislau Rezki <urezki@gmail.com>, Yu Zhao <yuzhao@google.com>,
dev@der-flo.net, Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-perf-users@vger.kernel.org, linux-mm@kvack.org,
linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH 0/3] x86/dumpstack: Inline copy_from_user_nmi()
Date: Mon, 19 Sep 2022 12:26:22 -0700 [thread overview]
Message-ID: <202209191225.B3A759134@keescook> (raw)
In-Reply-To: <YyiAz4gs4TvTqrvI@hirez.programming.kicks-ass.net>
On Mon, Sep 19, 2022 at 04:46:39PM +0200, Peter Zijlstra wrote:
> On Fri, Sep 16, 2022 at 12:57:23PM -0700, Andrew Morton wrote:
> > Why is this so complicated.
> >
> > There's virtually zero value in running all those debug checks from within
> > copy_from_user_nmi().
> >
> > --- a/arch/x86/lib/usercopy.c~a
> > +++ a/arch/x86/lib/usercopy.c
> > @@ -44,7 +44,7 @@ copy_from_user_nmi(void *to, const void
> > * called from other contexts.
> > */
> > pagefault_disable();
> > - ret = __copy_from_user_inatomic(to, from, n);
> > + ret = raw_copy_from_user(to, from, n);
> > pagefault_enable();
> >
> > return ret;
>
> I'm with Andrew here; this looks a *LOT* saner than all the other stuff.
Yeah, I'd agree -- it's a special case of a special case. I'll send a
new patch.
Thanks!
--
Kees Cook
next prev parent reply other threads:[~2022-09-19 19:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 13:59 [PATCH 0/3] x86/dumpstack: Inline copy_from_user_nmi() Kees Cook
2022-09-16 13:59 ` [PATCH 1/3] x86/uaccess: Move nmi_uaccess_okay() into uaccess.h Kees Cook
2022-09-16 13:59 ` [PATCH 2/3] x86/dumpstack: Inline copy_from_user_nmi() Kees Cook
2022-09-16 13:59 ` [PATCH 3/3] usercopy: Add find_vmap_area_try() to avoid deadlocks Kees Cook
2022-09-16 14:46 ` Matthew Wilcox
2022-09-16 15:09 ` Kees Cook
2022-09-16 19:15 ` Matthew Wilcox
2022-09-19 8:29 ` Uladzislau Rezki
2022-09-16 17:29 ` Uladzislau Rezki
2022-09-16 19:57 ` [PATCH 0/3] x86/dumpstack: Inline copy_from_user_nmi() Andrew Morton
2022-09-19 14:46 ` Peter Zijlstra
2022-09-19 19:26 ` Kees Cook [this message]
2022-09-17 2:20 ` Yu Zhao
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