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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25EC8C433EF for ; Thu, 12 May 2022 11:59:09 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KzVgH3pGXz3bxr for ; Thu, 12 May 2022 21:59:07 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=47.90.199.14; helo=out199-14.us.a.mail.aliyun.com; envelope-from=hsiangkao@linux.alibaba.com; receiver=) Received: from out199-14.us.a.mail.aliyun.com (out199-14.us.a.mail.aliyun.com [47.90.199.14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KzVg72S1Nz3bY8 for ; Thu, 12 May 2022 21:58:57 +1000 (AEST) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R201e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04426; MF=hsiangkao@linux.alibaba.com; NM=1; PH=DS; RN=5; SR=0; TI=SMTPD_---0VD-jm4z_1652356714; Received: from e18g06460.et15sqa.tbsite.net(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0VD-jm4z_1652356714) by smtp.aliyun-inc.com(127.0.0.1); Thu, 12 May 2022 19:58:40 +0800 From: Gao Xiang To: linux-erofs@lists.ozlabs.org, Chao Yu Subject: [PATCH] erofs: fix buffer copy overflow of ztailpacking feature Date: Thu, 12 May 2022 19:58:33 +0800 Message-Id: <20220512115833.24175-1-hsiangkao@linux.alibaba.com> X-Mailer: git-send-email 2.24.4 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gao Xiang , Yue Hu , LKML Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" I got some KASAN report as below: [ 46.959738] ================================================================== [ 46.960430] BUG: KASAN: use-after-free in z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188 ... [ 46.960430] Call Trace: [ 46.960430] [ 46.960430] dump_stack_lvl+0x41/0x5e [ 46.960430] print_report.cold+0xb2/0x6b7 [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] kasan_report+0x8a/0x140 [ 46.960430] ? z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] kasan_check_range+0x14d/0x1d0 [ 46.960430] memcpy+0x20/0x60 [ 46.960430] z_erofs_shifted_transform+0x2bd/0x370 [ 46.960430] z_erofs_decompress_pcluster+0xaae/0x1080 The root cause is that the tail pcluster won't be a complete filesystem block anymore. So if ztailpacking is used, the second part of an uncompresed tail pcluster may not be ``rq->pageofs_out``. Fixes: ab749badf9f4 ("erofs: support unaligned data decompression") Fixes: cecf864d3d76 ("erofs: support inline data decompression") Signed-off-by: Gao Xiang --- fs/erofs/decompressor.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 0f445f7e1df8..6dca1900c733 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -320,6 +320,7 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; const unsigned int righthalf = min_t(unsigned int, rq->outputsize, PAGE_SIZE - rq->pageofs_out); + const unsigned int lefthalf = rq->outputsize - righthalf; unsigned char *src, *dst; if (nrpages_out > 2) { @@ -342,10 +343,10 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, if (nrpages_out == 2) { DBG_BUGON(!rq->out[1]); if (rq->out[1] == *rq->in) { - memmove(src, src + righthalf, rq->pageofs_out); + memmove(src, src + righthalf, lefthalf); } else { dst = kmap_atomic(rq->out[1]); - memcpy(dst, src + righthalf, rq->pageofs_out); + memcpy(dst, src + righthalf, lefthalf); kunmap_atomic(dst); } } -- 2.24.4