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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 6FD70C4BA0B for ; Wed, 26 Feb 2020 08:11:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4BC4924650 for ; Wed, 26 Feb 2020 08:11:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727796AbgBZILt (ORCPT ); Wed, 26 Feb 2020 03:11:49 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:10694 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727341AbgBZILs (ORCPT ); Wed, 26 Feb 2020 03:11:48 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id A634F2CE09A151771A07; Wed, 26 Feb 2020 16:11:46 +0800 (CST) Received: from architecture4.huawei.com (10.160.196.180) by smtp.huawei.com (10.3.19.204) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 26 Feb 2020 16:11:36 +0800 From: Gao Xiang To: Chao Yu , CC: LKML , Miao Xie , "Gao Xiang" , Lasse Collin Subject: [PATCH v2 2/3] erofs: use LZ4_decompress_safe() for full decoding Date: Wed, 26 Feb 2020 16:10:07 +0800 Message-ID: <20200226081008.86348-2-gaoxiang25@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200226081008.86348-1-gaoxiang25@huawei.com> References: <20200226081008.86348-1-gaoxiang25@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.160.196.180] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As Lasse pointed out, "EROFS uses LZ4_decompress_safe_partial for both partial and full blocks. Thus when it is decoding a full block, it doesn't know if the LZ4 decoder actually decoded all the input. The real uncompressed size could be bigger than the value stored in the file system metadata. Using LZ4_decompress_safe instead of _safe_partial when decompressing a full block would help to detect errors." So it's reasonable to use _safe in case of potential corrupted images and it might have some speed gain as well although I didn't observe much difference. Note that legacy compressor (< 5.3, no LZ4_0PADDING) could encode extra data in a pcluster, which is excluded as well. Cc: Lasse Collin Fixes: 0ffd71bcc3a0 ("staging: erofs: introduce LZ4 decompression inplace") [ Gao Xiang: v5.3+, I will manually backport this to stable later. ] Signed-off-by: Gao Xiang --- fs/erofs/decompressor.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 5779a15c2cd6..cd978af6bdb9 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -157,9 +157,15 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out) } } - ret = LZ4_decompress_safe_partial(src + inputmargin, out, - inlen, rq->outputsize, - rq->outputsize); + /* legacy format could compress extra data in a pcluster. */ + if (rq->partial_decoding || !support_0padding) + ret = LZ4_decompress_safe_partial(src + inputmargin, out, + inlen, rq->outputsize, + rq->outputsize); + else + ret = LZ4_decompress_safe(src + inputmargin, out, + inlen, rq->outputsize); + if (ret < 0) { erofs_err(rq->sb, "failed to decompress, in[%u, %u] out[%u]", inlen, inputmargin, rq->outputsize); -- 2.17.1