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[23.128.96.18]) by mx.google.com with ESMTP id i3si1072340edj.574.2020.09.30.07.01.48; Wed, 30 Sep 2020 07:02:13 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=tjUAeQaV; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730432AbgI3N6Q (ORCPT + 99 others); Wed, 30 Sep 2020 09:58:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729903AbgI3N6P (ORCPT ); Wed, 30 Sep 2020 09:58:15 -0400 Received: from mail-ej1-x62d.google.com (mail-ej1-x62d.google.com [IPv6:2a00:1450:4864:20::62d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FFF9C061755 for ; Wed, 30 Sep 2020 06:58:15 -0700 (PDT) Received: by mail-ej1-x62d.google.com with SMTP id z23so2924136ejr.13 for ; Wed, 30 Sep 2020 06:58:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=48cYY9fCUs7qmGKNVy05KuGWxzPcUKDwzDxzj9tXpmI=; b=tjUAeQaVkXGGcEq5FhfrNYKu62uP/y55LgusVyQo5/NmXn4SLU2cLm+CB/ho9X+cO2 HZF0Khp7EqAVL+UwSiIQjMIfwcPkBE1Dt4HZ78Bzb/lUE9kTqdZGfRoJSxBkIpTfTPnH l/XA0oZyNXWDswzsW4ELzu22M6HRTACOpknMFPfDxo5Fu/Z8Y2tmn8mqOKcLJ0x5sVYH LWbOfPPi1FSFBpN4a7Nlev/OQWjL5JjEIyly2Tt73ucq0E1aNlPwiLSGnLYG79iGD5Qm CrQo0bPXg8MOc7d5dT6mKnstSNaOXjoYUMbFT1rEghjO/5tD4j74MqpsgIJ17A6cF0IZ ViEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=48cYY9fCUs7qmGKNVy05KuGWxzPcUKDwzDxzj9tXpmI=; b=CoqX/OU7VdL84rgYAjQRoJbMA/TY/XzNzvnNzTXrbZfWjKOX/s9MQQEx8yhjEisNfF 8m0yBCo65or+LnxiS9emAnYbwsETo/d//ZC+vggjw8xUQrFtc5+I1EAgM1gk7vRLlC8M XNHAHvdrwfBpnlvK8AmmIr1Ellyn4yMVbZLUcdcxel/IUnaJuQrYBRRUTbhLNcEI2EIL +zpSj83o7TL4AjUEno1pbK/WZ0xJBGe9GFJvMtDOfsscxmbTNCzEYKQeKQG2AgS1IoOQ xp6VUregE6VEvXn3Z8Dgn2Cklzf1PWPZC2Z7L1qesqjQ91+BSqJlHaBtWtkjlRjxZ5r8 5xXw== X-Gm-Message-State: AOAM530StIPV9qn1kNTH20TqiJnmVRL2btGkdTeI6zctcYMzn4yOs+nJ BxAD5QEs7HVHtTVhRu+Px00G3fqnvm9+5PGJh3DnunHQB/0= X-Received: by 2002:a17:906:4151:: with SMTP id l17mr3100975ejk.116.1601474293698; Wed, 30 Sep 2020 06:58:13 -0700 (PDT) MIME-Version: 1.0 References: <202009251301.A1FD183582@keescook> <202009251338.D17FB071@keescook> <202009251647.FD8CECD4@keescook> <202009260933.C603CD8@keescook> <202009281248.6F601005CA@keescook> In-Reply-To: <202009281248.6F601005CA@keescook> From: Pintu Agarwal Date: Wed, 30 Sep 2020 19:28:02 +0530 Message-ID: Subject: Re: KASLR support on ARM with Kernel 4.9 and 4.14 To: Kees Cook Cc: Ard Biesheuvel , Mark Rutland , Arnd Bergmann , Ard Biesheuvel , Marc Zyngier , Dave Martin , Kernelnewbies , Russell King - ARM Linux , open list , Tony Lindgren , matt@codeblueprint.co.uk, nico@linaro.org, Thomas Garnier , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 29 Sep 2020 at 01:20, Kees Cook wrote: > Note that I still can't explain what you're seeing. /proc/kallsyms > shouldn't be affected by these patches -- I would expect it to either > report the true value or 00s. > > > I will disable kptr_restrict and check or, I will enable > > CONFIG_DEBUG_CONSOLE_UNHASHED_POINTERS and check. > > I would start with kptr_restrict=0 and see if that changes the contents > of /proc/kallsyms. If it does, then it is the hashing. If it doesn't, > well, we're back to square one. :) Actually in that board, the kptr_restrict=0 already in both case: 4.9 and 4.14 Kernel boards. In another board with 4.14 and kptr_restrict=2, I see that the addresses are 00 always. I further checked that when I enable this config: CONFIG_DEBUG_CONSOLE_UNHASHED_POINTERS, then the addresses are remaining the same in every boot. But this particular config is not present in 4.9 Kernel. So, I think it is controlled using this config. -- Pintu