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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38B8EC433F5 for ; Thu, 11 Nov 2021 10:42:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 154916101C for ; Thu, 11 Nov 2021 10:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232905AbhKKKo7 (ORCPT ); Thu, 11 Nov 2021 05:44:59 -0500 Received: from szxga02-in.huawei.com ([45.249.212.188]:15816 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230256AbhKKKo6 (ORCPT ); Thu, 11 Nov 2021 05:44:58 -0500 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HqdZ75xLzz90nF; Thu, 11 Nov 2021 18:41:51 +0800 (CST) Received: from kwepemm600004.china.huawei.com (7.193.23.242) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.15; Thu, 11 Nov 2021 18:42:07 +0800 Received: from huawei.com (10.175.101.6) by kwepemm600004.china.huawei.com (7.193.23.242) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.15; Thu, 11 Nov 2021 18:42:06 +0800 From: Guo Xuenan To: CC: , , , , , , , , Subject: [PATCH v3] lz4: fix LZ4_decompress_safe_partial read out of bound Date: Thu, 11 Nov 2021 18:50:48 +0800 Message-ID: <20211111105048.2006070-1-guoxuenan@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111085058.1940591-1-guoxuenan@huawei.com> References: <20211111085058.1940591-1-guoxuenan@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemm600004.china.huawei.com (7.193.23.242) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When partialDecoding, it is EOF if we've either, filled the output buffer or can't proceed with reading an offset for following match. In some extreme corner cases when compressed data is crusted corrupted, UAF will occur. As reported by KASAN [1], LZ4_decompress_safe_partial may lead to read out of bound problem during decoding. lz4 upstream has fixed it [2] and this issue has been disscussed here [3] before. current decompression routine was ported from lz4 v1.8.3, bumping lib/lz4 to v1.9.+ is certainly a huge work to be done later, so, we'd better fix it first. [1] https://lore.kernel.org/all/000000000000830d1205cf7f0477@google.com/ [2] https://github.com/lz4/lz4/commit/c5d6f8a8be3927c0bec91bcc58667a6cfad244ad# [3] https://lore.kernel.org/all/CC666AE8-4CA4-4951-B6FB-A2EFDE3AC03B@fb.com/ Reported-by: syzbot+63d688f1d899c588fb71@syzkaller.appspotmail.com Cc: hsiangkao@linux.alibaba.com Cc: terrelln@fb.com Cc: cyan@fb.com Cc: cy.fan@huawei.com Signed-off-by: Guo Xuenan --- lib/lz4/lz4_decompress.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index 926f4823d5ea..fd1728d94bab 100644 --- a/lib/lz4/lz4_decompress.c +++ b/lib/lz4/lz4_decompress.c @@ -271,8 +271,12 @@ static FORCE_INLINE int LZ4_decompress_generic( ip += length; op += length; - /* Necessarily EOF, due to parsing restrictions */ - if (!partialDecoding || (cpy == oend)) + /* Necessarily EOF when !partialDecoding. + * When partialDecoding, it is EOF if we've either + * filled the output buffer or + * can't proceed with reading an offset for following match. + */ + if (!partialDecoding || (cpy == oend) || (ip >= (iend - 2))) break; } else { /* may overwrite up to WILDCOPYLENGTH beyond cpy */ -- 2.31.1