From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D26CBC11F6A for ; Sat, 10 Jul 2021 02:38:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B11E0613D6 for ; Sat, 10 Jul 2021 02:38:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234539AbhGJClW (ORCPT ); Fri, 9 Jul 2021 22:41:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:58446 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235802AbhGJCjr (ORCPT ); Fri, 9 Jul 2021 22:39:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1B05261439; Sat, 10 Jul 2021 02:36:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625884563; bh=kbisOGd3B+uqzPfIHDpDeTo7WJGM1uM+KCB1rcbZ+h4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dgY7az9bVc1VssC/DItFI0C2jbER91gSSz9qEsRO/iYEFvHng/mVeWydNe558MKAY uFbt7ki3p8hWh4+tcj4yfBdOzT/Mm9qgqp4d2j+phx2qUgVSfyhDNl+hkYBn8Ulk0D wsyp3G9SjMUDMz8cXyhzQD1RxNrtmh7qTP6WSKe58rwlFJBu4idwF0b+3LVqXRQ070 FyXl3tanTWHCNkuzjBuXPdkgKfevkZwmLL/glVgVcPxzC5Fynq0pNwTrDKo5pcEFee yC4EjZ4bktjqk7Ym/KIUWEHtuFIRmvBZYyqij/k32Cb5u6cHWEm3tYB1kKXH5cMBYg apHYQVHTQ1X8Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dimitri John Ledkov , Kyungsik Lee , Yinghai Lu , Bongkyu Kim , Kees Cook , Sven Schmidt <4sschmid@informatik.uni-hamburg.de>, Rajat Asthana , Nick Terrell , Gao Xiang , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL 4.14 33/33] lib/decompress_unlz4.c: correctly handle zero-padding around initrds. Date: Fri, 9 Jul 2021 22:35:15 -0400 Message-Id: <20210710023516.3172075-33-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210710023516.3172075-1-sashal@kernel.org> References: <20210710023516.3172075-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dimitri John Ledkov [ Upstream commit 2c484419efc09e7234c667aa72698cb79ba8d8ed ] lz4 compatible decompressor is simple. The format is underspecified and relies on EOF notification to determine when to stop. Initramfs buffer format[1] explicitly states that it can have arbitrary number of zero padding. Thus when operating without a fill function, be extra careful to ensure that sizes less than 4, or apperantly empty chunksizes are treated as EOF. To test this I have created two cpio initrds, first a normal one, main.cpio. And second one with just a single /test-file with content "second" second.cpio. Then i compressed both of them with gzip, and with lz4 -l. Then I created a padding of 4 bytes (dd if=/dev/zero of=pad4 bs=1 count=4). To create four testcase initrds: 1) main.cpio.gzip + extra.cpio.gzip = pad0.gzip 2) main.cpio.lz4 + extra.cpio.lz4 = pad0.lz4 3) main.cpio.gzip + pad4 + extra.cpio.gzip = pad4.gzip 4) main.cpio.lz4 + pad4 + extra.cpio.lz4 = pad4.lz4 The pad4 test-cases replicate the initrd load by grub, as it pads and aligns every initrd it loads. All of the above boot, however /test-file was not accessible in the initrd for the testcase #4, as decoding in lz4 decompressor failed. Also an error message printed which usually is harmless. Whith a patched kernel, all of the above testcases now pass, and /test-file is accessible. This fixes lz4 initrd decompress warning on every boot with grub. And more importantly this fixes inability to load multiple lz4 compressed initrds with grub. This patch has been shipping in Ubuntu kernels since January 2021. [1] ./Documentation/driver-api/early-userspace/buffer-format.rst BugLink: https://bugs.launchpad.net/bugs/1835660 Link: https://lore.kernel.org/lkml/20210114200256.196589-1-xnox@ubuntu.com/ # v0 Link: https://lkml.kernel.org/r/20210513104831.432975-1-dimitri.ledkov@canonical.com Signed-off-by: Dimitri John Ledkov Cc: Kyungsik Lee Cc: Yinghai Lu Cc: Bongkyu Kim Cc: Kees Cook Cc: Sven Schmidt <4sschmid@informatik.uni-hamburg.de> Cc: Rajat Asthana Cc: Nick Terrell Cc: Gao Xiang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- lib/decompress_unlz4.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/lib/decompress_unlz4.c b/lib/decompress_unlz4.c index 1b0baf3008ea..b202aa864c48 100644 --- a/lib/decompress_unlz4.c +++ b/lib/decompress_unlz4.c @@ -115,6 +115,9 @@ STATIC inline int INIT unlz4(u8 *input, long in_len, error("data corrupted"); goto exit_2; } + } else if (size < 4) { + /* empty or end-of-file */ + goto exit_3; } chunksize = get_unaligned_le32(inp); @@ -128,6 +131,10 @@ STATIC inline int INIT unlz4(u8 *input, long in_len, continue; } + if (!fill && chunksize == 0) { + /* empty or end-of-file */ + goto exit_3; + } if (posp) *posp += 4; @@ -187,6 +194,7 @@ STATIC inline int INIT unlz4(u8 *input, long in_len, } } +exit_3: ret = 0; exit_2: if (!input) -- 2.30.2