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 7ECBBC433F5 for ; Thu, 11 Nov 2021 08:42:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5BA1C610F7 for ; Thu, 11 Nov 2021 08:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232322AbhKKIpJ (ORCPT ); Thu, 11 Nov 2021 03:45:09 -0500 Received: from szxga02-in.huawei.com ([45.249.212.188]:26301 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229674AbhKKIpG (ORCPT ); Thu, 11 Nov 2021 03:45:06 -0500 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HqZpY1Cx3zbhpP; Thu, 11 Nov 2021 16:37:25 +0800 (CST) Received: from kwepemm600004.china.huawei.com (7.193.23.242) by dggemv711-chm.china.huawei.com (10.1.198.66) 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 16:42:09 +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 16:42:08 +0800 From: Guo Xuenan To: CC: , , , , , , , , Subject: [PATCH v2] lz4: fix LZ4_decompress_safe_partial read out of bound Date: Thu, 11 Nov 2021 16:50:58 +0800 Message-ID: <20211111085058.1940591-1-guoxuenan@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111071759.1825086-1-guoxuenan@huawei.com> References: <20211111071759.1825086-1-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: dggems706-chm.china.huawei.com (10.3.19.183) 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 crupted, 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/netdev/000000000000374f8905ce173204@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