linux-kernel - Re: [PATCH] x86, random: Fix get_random_bytes() warning in x86 start

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Message-ID: <20180529160743.GA7381@thunk.org>
Date:   Tue, 29 May 2018 12:07:43 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Prarit Bhargava <prarit@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rik van Riel <riel@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Kate Stewart <kstewart@...uxfoundation.org>
Subject: Re: [PATCH] x86, random: Fix get_random_bytes() warning in x86
 start_kernel

On Tue, May 29, 2018 at 11:01:07AM -0400, Prarit Bhargava wrote:
> Kees, in early boot no pool is available so the stack canary is initialized from
> the TSC.  Later in boot, the stack canary will use the the crng.
> 
> ie) in early boot only TSC is okay, and late boot (when crng_ready() is true)
> the pool will be used.

But that means all of the kernel threads (e.g., workqueues, et. al)
would not be well protected by the stack canary.  That
seems.... rather unfortunate.

      	     	  	      	   	     - Ted