From: Julian Stecklina <jsteckli@amazon.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Julian Stecklina <js@alien8.de>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
hpa@zytor.com, linux-kernel@vger.kernel.org, jschoenh@amazon.de,
Dave Jiang <dave.jiang@intel.com>,
Kees Cook <keescook@chromium.org>, Baoquan He <bhe@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/2] x86/boot: increase maximum number of avoided KASLR regions
Date: Wed, 06 Feb 2019 13:50:57 +0100 [thread overview]
Message-ID: <ciirm8womdaxn2.fsf@u54ee758033e858cfa736.ant.amazon.com> (raw)
In-Reply-To: <20190205144441.GS21801@zn.tnic> (Borislav Petkov's message of "Tue, 5 Feb 2019 15:44:41 +0100")
Borislav Petkov <bp@alien8.de> writes:
>> @@ -213,7 +213,7 @@ static void mem_avoid_memmap(char *str)
>> i++;
>> }
>>
>> - /* More than 4 memmaps, fail kaslr */
>> + /* Can't store all regions, fail kaslr */
>> if ((i >= MAX_MEMMAP_REGIONS) && str)
>> memmap_too_large = true;
>> }
>> --
>
> Lemme add some of the folks from
> f28442497b5caf7bf573ade22a7f8d3559e3ef56 to Cc.
>
> It all looks arbitrary to me: first 4 unusable memmap regions, this
> patch raises it to 16. Why are we even imposing such a limit?
Because at this point, we are not in a good position to handle an
unlimited amount of regions.
As for the choice of "16", I took our usecase and multiplied it by two.
FWIW, this could be even larger.
Julian
next prev parent reply other threads:[~2019-02-06 12:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 16:40 [PATCH 1/2] x86/boot: fix KASL when memmap range manipulation is used Julian Stecklina
2019-01-30 16:40 ` [PATCH 2/2] x86/boot: increase maximum number of avoided KASLR regions Julian Stecklina
2019-02-05 14:44 ` Borislav Petkov
2019-02-06 12:50 ` Julian Stecklina [this message]
2019-02-06 14:17 ` Borislav Petkov
2019-02-06 15:29 ` Kees Cook
2019-02-06 17:53 ` Borislav Petkov
2019-02-11 9:09 ` [PATCH 1/2] x86/boot: fix KASL when memmap range manipulation is used Baoquan He
2019-02-11 9:54 ` Julian Stecklina
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