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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 4C307C43387 for ; Tue, 8 Jan 2019 19:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 179FE20660 for ; Tue, 8 Jan 2019 19:58:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546977529; bh=f1MsrB64D5ogQt73dYUl6yOvYVFSpjYIz/QsTbS/Beo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vcRDEKHpZUaDkXrHE5gzs4hx2oY+YGMgOTxTm6l1UGEVMW7HU0gsJAzlw6hBH4OFP 7z6s1WOdAqaWP3Mr/xtACJvNIa8/ithcdJl7evPeSUd8oE04OJUvx/L6dAWVehk3uG bVp6s/E/lJBedMfgLv/pMw9yJ6JgZYvkrPB+ZOqM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729581AbfAHT6m (ORCPT ); Tue, 8 Jan 2019 14:58:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:36932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730399AbfAHT3a (ORCPT ); Tue, 8 Jan 2019 14:29:30 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 454C52183F; Tue, 8 Jan 2019 19:29:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975769; bh=f1MsrB64D5ogQt73dYUl6yOvYVFSpjYIz/QsTbS/Beo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nwlKDcIHJf7IOvgdlFWzXbGQBcJK8NUa75jzdLJhQ/ZPFfOdkujF6u6Qj2iMw0ng2 zb0DJVvHxuvcomJFbyK7tf4nnXAdjdClkoNHqkJAlCkxySyawV3pEIp00Plp5yMd+6 Mqe5x6/r6gall2F9qGWy0grxKX8N2bVf4oT7xgac= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Sandeen , Eric Sandeen , "Darrick J . Wong" , Sasha Levin , linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 4.20 110/117] iomap: don't search past page end in iomap_is_partially_uptodate Date: Tue, 8 Jan 2019 14:26:18 -0500 Message-Id: <20190108192628.121270-110-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108192628.121270-1-sashal@kernel.org> References: <20190108192628.121270-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Sandeen [ 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 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages, } 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