From nobody Thu Sep 18 02:40:03 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB71EC4332F for ; Tue, 13 Dec 2022 10:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234791AbiLMKf2 (ORCPT ); Tue, 13 Dec 2022 05:35:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235103AbiLMKfL (ORCPT ); Tue, 13 Dec 2022 05:35:11 -0500 Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A391EE13 for ; Tue, 13 Dec 2022 02:35:10 -0800 (PST) Received: by mail-wr1-x42e.google.com with SMTP id h12so15102135wrv.10 for ; Tue, 13 Dec 2022 02:35:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.huji.ac.il; s=mailhuji; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=kJM6rNGnsSsKkdiUVZXoWgZhZ1P+6n693//gXJy6sCg=; b=ImrOxdJZ4ry+gv05nHH385ZDSpbyw6yNwCyHb9Ouf1tAsDnAoEC7NE/Pkf9xzcajDF 1WC2rtDOARBqEHm0IBk8BC507qvOFgIz+ISubOBvngpH82Wnx7G+Y2y+pcB8lKibMFYB wzP3lPcUuuFXvypAulFIxjUxaO6y+Ww8TNGUs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=kJM6rNGnsSsKkdiUVZXoWgZhZ1P+6n693//gXJy6sCg=; b=CBfmBoBLkQP7tyuz7dFK1dZ++r6wpwbQ3tP0pIILUFGx2BY3M5mBp93AmaS9ruZoMg fIIhP5NIEz1BZnnNKnbJ9+/5kbU58/+RIesqs7N4zK6FOftPfMgb6uuwBtKGJGSoApuU TffWPESeyk10fkdXKQWF4ch/DAjF3OWLY+cXmIkNqPMe2e7nL29Iwaus9XAELYKKTVyZ qkP5F8Oc7aDs5SvURGGtF/1IBmFtduvuomYEKMqiAMHgBZhzJ6SznuGZ49fX/buuGpWR +EjENn8k2o2i9ugguVPX6YHydJoWkJ9RZDEpai+1oXWj5paEidvN7j5I7MjSXVx0EVCm On3w== X-Gm-Message-State: ANoB5pn6z/rJU3rZCNRmgQOyz3/gCSbVEybhBSEo1P0Rs8ylQskAaRn+ 8fmHFIG3MIoJYUanmuiThxffTPGsbwj3ApwnrxjJdTWQAyO8eSj2Z52wwkf/kgArDhARhQkRsbJ cCuJZZPcelrOtx9Ztp6miQCsLLntHRRucNup6Vl/yl3pCxsMQBLOfZJ3UZbO+jMaTGmcfrTZYHU +N2vQwUzM7NWWXpSXPL3IiYjI= X-Google-Smtp-Source: AA0mqf5+7prvxB1ns5rL2RiclPDy4aLD/HkJ3wtquHbTwD+WQBoIDzHHAJ58XXdcenOUDVB6CEdPOA== X-Received: by 2002:a5d:6a46:0:b0:242:149c:6d29 with SMTP id t6-20020a5d6a46000000b00242149c6d29mr10543782wrw.16.1670927708804; Tue, 13 Dec 2022 02:35:08 -0800 (PST) Received: from MacBook-Pro-6.lan ([2a0d:6fc2:218c:1a00:a0bd:cef2:7a82:b529]) by smtp.gmail.com with ESMTPSA id v15-20020a5d6b0f000000b002366553eca7sm11295813wrw.83.2022.12.13.02.35.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 02:35:08 -0800 (PST) From: david.keisarschm@mail.huji.ac.il To: linux-kernel@vger.kernel.org, Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" Cc: David , aksecurity@gmail.com, ilay.bahat1@gmail.com Subject: [PATCH v2 3/3] Replace invocation of weak PRNG in arch/x86/mm/kaslr.c Date: Tue, 13 Dec 2022 12:34:59 +0200 Message-Id: X-Mailer: git-send-email 2.38.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: David We changed the invocation of prandom_bytes_state which is considered weak to get_random_bytes. We also omitted the call to the seeding function, since get_random_bytes matintains its own state, so there is no need for seeding here anymore. This is important for the memory initial state randomization. Signed-off-by: David --- arch/x86/mm/kaslr.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index 0bb083979..9ef8993d5 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -66,7 +66,6 @@ void __init kernel_randomize_memory(void) size_t i; unsigned long vaddr_start, vaddr; unsigned long rand, memory_tb; - struct rnd_state rand_state; unsigned long remain_entropy; unsigned long vmemmap_size; =20 @@ -113,8 +112,6 @@ void __init kernel_randomize_memory(void) for (i =3D 0; i < ARRAY_SIZE(kaslr_regions); i++) remain_entropy -=3D get_padding(&kaslr_regions[i]); =20 - prandom_seed_state(&rand_state, kaslr_get_random_long("Memory")); - for (i =3D 0; i < ARRAY_SIZE(kaslr_regions); i++) { unsigned long entropy; =20 @@ -123,7 +120,7 @@ void __init kernel_randomize_memory(void) * available. */ entropy =3D remain_entropy / (ARRAY_SIZE(kaslr_regions) - i); - prandom_bytes_state(&rand_state, &rand, sizeof(rand)); + get_random_bytes(&rand, sizeof(rand)); entropy =3D (rand % (entropy + 1)) & PUD_MASK; vaddr +=3D entropy; *kaslr_regions[i].base =3D vaddr; --=20 2.38.0