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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 EA76BC282C3 for ; Thu, 24 Jan 2019 19:44:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4917218D9 for ; Thu, 24 Jan 2019 19:44:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548359084; bh=aqrjrh3vkfg2ehDT8Mqr8uZRo513rab+qqJsNK9soY0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hV/KG7PdVb7g/zg7og0uGhHBwTBa8ZUfcf8s1o4N+pQ2dCNyNlAx4qcgUvLylvZ6h lrOP6QgwCpjxpLk3Ih717OukyVu60op/tBtkPEsIq8pLDRNHzbAPhe5h2sV+l/6w/0 /O06Rzsc9wckDZUQkP3vMlLGGtG4RDOydC3NyO9Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388116AbfAXTom (ORCPT ); Thu, 24 Jan 2019 14:44:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:45512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733296AbfAXTok (ORCPT ); Thu, 24 Jan 2019 14:44:40 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C1C2218D2; Thu, 24 Jan 2019 19:44:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548359079; bh=aqrjrh3vkfg2ehDT8Mqr8uZRo513rab+qqJsNK9soY0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RUYTJ+1Hzy66gNhK8BJSB638uDngBiGX4qOSbdR2rLmXPEMZMd4SqMRbyIRrL1y2e uS+fAO2VETMgi/CLFCxjQEaDWMdufkKZFzxs75O3MN6JOFzRf90zusJe5zvu91GVVA OMOzXXfFXy2c7ahvMZh/dbmIgQeuOtIvEFljCrdc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zorro Lang , Eric Sandeen , Eric Sandeen , "Darrick J. Wong" , Sasha Levin Subject: [PATCH 4.20 114/127] iomap: dont search past page end in iomap_is_partially_uptodate Date: Thu, 24 Jan 2019 20:21:00 +0100 Message-Id: <20190124190216.814097492@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190124190211.984305387@linuxfoundation.org> References: <20190124190211.984305387@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 3cc31fa65d85610574c0f6a474e89f4c419923d5 ] iomap_is_partially_uptodate() is intended to check wither blocks within the selected range of a not-uptodate page are uptodate; if the range we care about is up to date, it's an optimization. However, the iomap implementation continues to check all blocks up to from+count, which is beyond the page, and can even be well beyond the iop->uptodate bitmap. I think the worst that will happen is that we may eventually find a zero bit and return "not partially uptodate" when it would have otherwise returned true, and skip the optimization. Still, it's clearly an invalid memory access that must be fixed. So: fix this by limiting the search to within the page as is done in the non-iomap variant, block_is_partially_uptodate(). Zorro noticed thiswhen KASAN went off for 512 byte blocks on a 64k page system: BUG: KASAN: slab-out-of-bounds in iomap_is_partially_uptodate+0x1a0/0x1e0 Read of size 8 at addr ffff800120c3a318 by task fsstress/22337 Reported-by: Zorro Lang Signed-off-by: Eric Sandeen Signed-off-by: Eric Sandeen Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Sasha Levin --- fs/iomap.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/fs/iomap.c b/fs/iomap.c index d6bc98ae8d35..ce837d962d47 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -492,16 +492,29 @@ done: } EXPORT_SYMBOL_GPL(iomap_readpages); +/* + * iomap_is_partially_uptodate checks whether blocks within a page are + * uptodate or not. + * + * Returns true if all blocks which correspond to a file portion + * we want to read within the page are uptodate. + */ int iomap_is_partially_uptodate(struct page *page, unsigned long from, unsigned long count) { struct iomap_page *iop = to_iomap_page(page); struct inode *inode = page->mapping->host; - unsigned first = from >> inode->i_blkbits; - unsigned last = (from + count - 1) >> inode->i_blkbits; + unsigned len, first, last; unsigned i; + /* Limit range to one page */ + len = min_t(unsigned, PAGE_SIZE - from, count); + + /* First and last blocks in range within page */ + first = from >> inode->i_blkbits; + last = (from + len - 1) >> inode->i_blkbits; + if (iop) { for (i = first; i <= last; i++) if (!test_bit(i, iop->uptodate)) -- 2.19.1