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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 D1A74C43460 for ; Mon, 17 May 2021 14:34:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACE0B61C87 for ; Mon, 17 May 2021 14:34:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240421AbhEQOeQ (ORCPT ); Mon, 17 May 2021 10:34:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:53812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239209AbhEQO2U (ORCPT ); Mon, 17 May 2021 10:28:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8F10B613DD; Mon, 17 May 2021 14:14:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621260863; bh=YtWrpDksy16CNvy7ZUAIzG9IVLdgDnmTWjRg9TIdu1A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZdM+qFFdPDtMMCWY5XeTfBAGoh0ymgK+ClIOKVDhQmMeBF/sH/QC299NMIirREz0C Ono6QMIvZPuDMKtEyYsfRZLFwXx8BYUzq8jYwa7lasIGl4F4EMUO72vpcIkOE7hPJ2 osfThFEXlUdEFCECHcOS2bxMeGngWjzZmg0VxC6g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Phillip Lougher , syzbot+e8f781243ce16ac2f962@syzkaller.appspotmail.com, syzbot+7b98870d4fec9447b951@syzkaller.appspotmail.com, Andrew Morton , Linus Torvalds Subject: [PATCH 5.12 255/363] squashfs: fix divide error in calculate_skip() Date: Mon, 17 May 2021 16:02:01 +0200 Message-Id: <20210517140311.219791555@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140302.508966430@linuxfoundation.org> References: <20210517140302.508966430@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Phillip Lougher commit d6e621de1fceb3b098ebf435ef7ea91ec4838a1a upstream. Sysbot has reported a "divide error" which has been identified as being caused by a corrupted file_size value within the file inode. This value has been corrupted to a much larger value than expected. Calculate_skip() is passed i_size_read(inode) >> msblk->block_log. Due to the file_size value corruption this overflows the int argument/variable in that function, leading to the divide error. This patch changes the function to use u64. This will accommodate any unexpectedly large values due to corruption. The value returned from calculate_skip() is clamped to be never more than SQUASHFS_CACHED_BLKS - 1, or 7. So file_size corruption does not lead to an unexpectedly large return result here. Link: https://lkml.kernel.org/r/20210507152618.9447-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Reported-by: Reported-by: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/squashfs/file.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -211,11 +211,11 @@ failure: * If the skip factor is limited in this way then the file will use multiple * slots. */ -static inline int calculate_skip(int blocks) +static inline int calculate_skip(u64 blocks) { - int skip = blocks / ((SQUASHFS_META_ENTRIES + 1) + u64 skip = blocks / ((SQUASHFS_META_ENTRIES + 1) * SQUASHFS_META_INDEXES); - return min(SQUASHFS_CACHED_BLKS - 1, skip + 1); + return min((u64) SQUASHFS_CACHED_BLKS - 1, skip + 1); }