From patchwork Sat Feb 17 06:25:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 202577 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:693c:2685:b0:108:e6aa:91d0 with SMTP id mn5csp173544dyc; Fri, 16 Feb 2024 22:26:34 -0800 (PST) X-Forwarded-Encrypted: i=3; AJvYcCVlWGBPAIYKW+wh6/+sLLc4mMUspdW5DdcbMf7+lYZvQ7ST613gJ32suIKMQKy63iuNQYmoZeLXcKgBLP8MdPvv6fYi4Q== X-Google-Smtp-Source: AGHT+IFDH5w+67ziql8X35AKSDtpbdo/q5GgS0MP2xKMYrOOnrdwzOjJ5F3POwZdbvlHIm1sMRUF X-Received: by 2002:a17:902:7843:b0:1da:2a91:8c08 with SMTP id e3-20020a170902784300b001da2a918c08mr6309205pln.3.1708151194560; Fri, 16 Feb 2024 22:26:34 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1708151194; cv=pass; d=google.com; s=arc-20160816; b=p+/Q59Jj+dNhFOYVNXZaebRsehvm4FCvtTUxzVLh7YMmMXyn8yTZwn2G9P9c4EXZIt 7wwLhEN3l1vdXJ5HqL8tU7XBnqexRTtbSm1uQJvhzyQppMD60gvMLkm/pjkW5D10nZJe G1CaWEDlD4XAx4N4osHzi2BSevhYJcOo8sB2HX5NXSVZbFo/dt381mt3wYDmOJdJDRuJ qTc23YO4B0EnTAlUpAzhrjRNr5l8ZAHytYh+1VgmU6q/1vAHKOtV50+fgnprr2MuOByA BT8g/+Oix1Ar54KgXe8cnj3lys0upPjv70mELCRdOOo+4RFGdVygjOrs0Cw3KJF6gQyr +ewA== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:list-unsubscribe :list-subscribe:list-id:precedence:references:in-reply-to:message-id :date:subject:cc:to:from:dkim-signature; bh=E2RXdELjA1+Y5TPLiUTm0d2mhfp+RAxxenDK5Rv9UCY=; fh=rPeLNfqiFDVU1s1XEm3gdyWMG2ndkuDM/JMQcegZ5v4=; b=ijRbx6iE65/qMy9MTQVEdyBsaeALDiwiAhvV14XqNT3PGXTzbqwNVlOqgWFe+Ow6Ba 63YhMudEyDsl4rZ/Gr369zNysY3sTpH91S/w387SX3spQVP0nV8EA2GWdn1Nko7VLro8 15K/s+4dAx/qHz+BmAnGPkkpjBW8+UP55IxFi+Y5hWvcQLfTLeriAfTIpQYtq1uxUsbt +lzmG8GNkLuLeBF0yXd6HskFRpzvlrtx1UbWpfbkVM71DyI1vO+6naYmVMIGD3GDPVJj MWgtuOFslC0zhIwn3lsTpyvXdfZnsuewdAxMOGfdM+8Pkbp4mGQccqgcnj1aVc30t1Zq FmhA==; dara=google.com ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=PSM2Juy3; arc=pass (i=1 spf=pass spfdomain=chromium.org dkim=pass dkdomain=chromium.org dmarc=pass fromdomain=chromium.org); spf=pass (google.com: domain of linux-kernel+bounces-69706-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-69706-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from sv.mirrors.kernel.org (sv.mirrors.kernel.org. [2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id x8-20020a170902a38800b001db5fc15a7csi1052671pla.451.2024.02.16.22.26.34 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Feb 2024 22:26:34 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-69706-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=PSM2Juy3; arc=pass (i=1 spf=pass spfdomain=chromium.org dkim=pass dkdomain=chromium.org dmarc=pass fromdomain=chromium.org); spf=pass (google.com: domain of linux-kernel+bounces-69706-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-69706-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 60E31282BCE for ; Sat, 17 Feb 2024 06:26:34 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5D2A21D685; Sat, 17 Feb 2024 06:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="PSM2Juy3" Received: from mail-pg1-f170.google.com (mail-pg1-f170.google.com [209.85.215.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E6E291CA9B for ; Sat, 17 Feb 2024 06:25:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708151150; cv=none; b=Mla8fRce7xxNNwlrKflqzeSHJ/TKIdBT1MCnIBfRxXUatkmqVYZOFMnQPiAOI+F0VMySw0gxud3vsoBxVlUxFdoMVCPRh14iqoYEFCjemI1kG8OApzTifKXid8bOvfbpv9tEuq/91WUO0Iz9RlQ0MzcqiSIplYFOP81F7e3HHUs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708151150; c=relaxed/simple; bh=Y9GWQSNdeMe/TiCQJCjXENrVrfi7E3amSjOSWzM2S1o=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CLqZDkQxHoSbDZ9MKLPdcOT6RtZnBUbuDNN2ZCwTnVJngIV9ye4zgaAKVXN4BuCUO6iwGrlgLkZ6nZeaDASUr03rk8UXuijpvQdMwbpJkJ0UTeOzOFxdkyMShkc2zNjfCHXT6uYin2mFNxqTC8HM5v8E54vqtq/8NCMTRu0iGoY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=PSM2Juy3; arc=none smtp.client-ip=209.85.215.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Received: by mail-pg1-f170.google.com with SMTP id 41be03b00d2f7-5d3907ff128so2332574a12.3 for ; Fri, 16 Feb 2024 22:25:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1708151147; x=1708755947; darn=vger.kernel.org; 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=E2RXdELjA1+Y5TPLiUTm0d2mhfp+RAxxenDK5Rv9UCY=; b=PSM2Juy3NgnPRmxXplM3Wgy7959T+vLMrYBXBrlbGwTI4LRMympMzyf7Oba6Kxq+M0 oLkEU/4veTGKHBrBNvnNeXue0AEP1spIBpvIvX+eYMlFgP3lCl//sJc5aUhqjeNGVwX4 0IhOfT2NCGli2rJy/vCZS4aywrhoQOywPKfxU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708151147; x=1708755947; 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=E2RXdELjA1+Y5TPLiUTm0d2mhfp+RAxxenDK5Rv9UCY=; b=JcQbU24FWWDKf1v24o8WBFSXKO7tMBI7ORFyfVsvsw2sjSL710+p116rW/VdZGZyRy cN+9I6dPK9nNkh+gKJ2Ix6eZyCwDcSGsrrScN6+uJRyPUadHg6G/BetWdd8LHST1txy4 wAdZnmkfMv3WRH0A20YUHXJUIHYrbuLK/wiMNo5yCMPJhDXyEiRIGVsZdZBAu1zi1g5b Z4i7N20l41qeHdTkH8/L4EYq1vRcFm/v38aaXy02XmDmq6XrNfU2KeOhOdVMsUoJ84Aa ZqM8wtBmDeBY2/y7bS8UWd7rcXo9MRfu3jiVh8Pka/pqsrZmcY6gPqnJ/Rto2jUieRu5 Aoyw== X-Forwarded-Encrypted: i=1; AJvYcCV5UsqeHzS+IwB3G1hZYFjzO1uG9UwmFEuGtgpIVCksnWjHjy9GlybAMFNMoEHtqjd0a+TbLuHnGNmdzbCDsnNp6KcnYxRRfNizyDMH X-Gm-Message-State: AOJu0YxkZ4Xh//1h4tu+WGwZKyj131op8F7pPDNGrsoYbTxm/9Os/n26 Y2LWpe4zeaekdhrOvIbTuD1OWsLHAJIOFpdB4ej16z5faBpJUwwwz2G5oqa7xo9UgekTh4oLeVw = X-Received: by 2002:a17:902:e80d:b0:1d9:427a:991 with SMTP id u13-20020a170902e80d00b001d9427a0991mr8385363plg.20.1708151147280; Fri, 16 Feb 2024 22:25:47 -0800 (PST) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id mm11-20020a1709030a0b00b001db6da30331sm788247plb.86.2024.02.16.22.25.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Feb 2024 22:25:46 -0800 (PST) From: Kees Cook To: Jiri Kosina Cc: Kees Cook , y0un9n132@gmail.com, Geert Uytterhoeven , Alexander Viro , Christian Brauner , Jan Kara , Eric Biederman , Christophe Leroy , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Peter Zijlstra , Qi Zheng , Alexandre Ghiti , Josh Poimboeuf , "Kirill A. Shutemov" , Rick Edgecombe , Brian Gerst , Bjorn Helgaas , Tony Battersby , linux-kernel@vger.kernel.org, x86@kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH 2/2] binfmt_elf: Leave a gap between .bss and brk Date: Fri, 16 Feb 2024 22:25:44 -0800 Message-Id: <20240217062545.1631668-2-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240217062035.work.493-kees@kernel.org> References: <20240217062035.work.493-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1512; i=keescook@chromium.org; h=from:subject; bh=Y9GWQSNdeMe/TiCQJCjXENrVrfi7E3amSjOSWzM2S1o=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBl0FFoSMLWKnRZV/Xpg3nYIyPCuv0NWoUMuFI3f ssQMNwOx8mJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZdBRaAAKCRCJcvTf3G3A JvXFD/0ZGY+pv/RW0jEwUr/fOJKrMeYvRA+q8dAhwBU4yZf/9WvOK1OItaQt6erwqczIQcGDsKX RWFEhlQbXwgzOXrwCvEVU3X/MwTvOZFnZ0wTXOJZIuqX6uhvJuDZYq+kDfDixzSf+vvZ5N5gZBO TJzXBbBFV7TqO+okj4IS3xOJWZewgGjhNT8vbeQcPdzj69HDDkXXfpLkoSfygpZcWqlp9XDZiNy vXK3r7lesiRP3IhhoJj7l67XzCYktFTMcgxwx7uHCkePYddv5NSQpYuV1e3GrWYPneqbU/ta/RX cWwsnNmxh2abzRU47UKh05W/uYImIbey5l0CSZI/7QN6m152TAREIrmIXwl2k22fjZgwgd+Apv8 4oW4U/bqzoG9w1PMnHKDMQ9jsdEQB9hjMCKn8XCd+7Gv1wyNPPDXV5RFfLYuFJeaPMBdmXP7zFy E345+0/LhEK6UZl9XBsjpHxXtro8hrLNXyQJNR0dzipAEXd7VeizjMBrL4dibLwpq9Vt5GEwcbV rdHrk6W8yGkeyTm7dflKIXZxINWwAC8JEcnyTOaMiaSf+7Trt7zTSHdjJwqs75llY8Q2hwdTTG3 H4HQ8+CnaTwekWZMYV2AJy4oOxU2TWbO/56rrPwpm2xEE837qZM9Jz9EeaTLbA9t0NKKZotRk7n IeAJGDC3TTWSd+A== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1791126346840204137 X-GMAIL-MSGID: 1791126346840204137 Currently the brk starts its randomization immediately after .bss, which means there is a chance that when the random offset is 0, linear overflows from .bss can reach into the brk area. Leave at least a single page gap between .bss and brk (when it has not already been explicitly relocated into the mmap range). Reported-by: y0un9n132@gmail.com Closes: https://lore.kernel.org/linux-hardening/CA+2EKTVLvc8hDZc+2Yhwmus=dzOUG5E4gV7ayCbu0MPJTZzWkw@mail.gmail.com/ Signed-off-by: Kees Cook --- Cc: Jiri Kosina Cc: Geert Uytterhoeven Cc: Alexander Viro Cc: Christian Brauner Cc: Jan Kara Cc: Eric Biederman Cc: Christophe Leroy Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org --- fs/binfmt_elf.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 5397b552fbeb..7862962f7a85 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1262,6 +1262,9 @@ static int load_elf_binary(struct linux_binprm *bprm) if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && elf_ex->e_type == ET_DYN && !interpreter) { mm->brk = mm->start_brk = ELF_ET_DYN_BASE; + } else { + /* Otherwise leave a gap between .bss and brk. */ + mm->brk = mm->start_brk = mm->brk + PAGE_SIZE; } mm->brk = mm->start_brk = arch_randomize_brk(mm);