From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Prarit Bhargava <prarit@redhat.com>
Cc: <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
<x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Philippe Ombredanne <pombredanne@nexb.com>,
Kees Cook <keescook@chromium.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Kate Stewart <kstewart@linuxfoundation.org>
Subject: Re: [PATCH v2] x86, random: Fix get_random_bytes() warning in x86 start_kernel
Date: Mon, 4 Feb 2019 10:55:35 -0500 [thread overview]
Message-ID: <20190204155535.GC9802@mit.edu> (raw)
In-Reply-To: <4adb711f-f81e-31ef-c581-4d5ecc739bd1@redhat.com>
On Sun, Feb 03, 2019 at 08:09:37AM -0500, Prarit Bhargava wrote:
> Ted, the bug I'm trying to fix is the warning:
>
> random: get_random_bytes called from start_kernel+0x8e/0x587 with crng_init=0
>
> during early boot. Even with the kernel parameter the warning appears.
Sometimes the warnings are real, and shouldn't be suppressed. A
Debian maintainer once tried to suppress a compile-time warning, and
it was disastrous for security. :-)
What line number is that corresponding to? It sounds like something
is trying to use get_random_bytes() before the random driver was
initialized, and so the first question is does it really need to call
get_random_bytes() then or can it be moved?
> > Also, relying on the TSC for entropy is not something we should be
> > recommending.
>
> The current code uses the TSC. It is not something new I'm introducing.
But we don't *rely* on it. That's a big difference.
- Ted
next prev parent reply other threads:[~2019-02-04 15:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-01 18:08 [PATCH v2] x86, random: Fix get_random_bytes() warning in x86 start_kernel Prarit Bhargava
2019-02-02 3:02 ` Theodore Y. Ts'o
2019-02-03 13:09 ` Prarit Bhargava
2019-02-04 15:55 ` Theodore Y. Ts'o [this message]
2019-02-08 13:14 ` Prarit Bhargava
2019-02-08 17:43 ` Theodore Y. Ts'o
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