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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14D0CC43334 for ; Tue, 7 Jun 2022 21:33:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380061AbiFGVdv (ORCPT ); Tue, 7 Jun 2022 17:33:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359517AbiFGUfq (ORCPT ); Tue, 7 Jun 2022 16:35:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 530011EAF2; Tue, 7 Jun 2022 11:37:54 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3FBFBB8237F; Tue, 7 Jun 2022 18:37:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97652C385A2; Tue, 7 Jun 2022 18:37:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654627069; bh=u7ZIt0Mxn6nLQ2SNVIueveazrS/E5Xd4kCtZ5F653Dk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ToVZuZOQMNaYJCxEuoXDGwImLPNklwUT7RtPD+LFkd0vUOBpcQpdeWc9ATlTZu6km s5U00DGrqK9OSh0ypJ+L2fVwqarA/4bNDHFE3pEVFJthSFWDaF/T/QE2sXhcxxunCt MIKBLnSHQK1kqqzJYKBnCy6JUgyEYnP8K600yB0g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jakob Koschel , Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.17 565/772] f2fs: fix dereference of stale list iterator after loop body Date: Tue, 7 Jun 2022 19:02:37 +0200 Message-Id: <20220607165005.604542807@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164948.980838585@linuxfoundation.org> References: <20220607164948.980838585@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: Jakob Koschel [ Upstream commit 2aaf51dd39afb6d01d13f1e6fe20b684733b37d5 ] The list iterator variable will be a bogus pointer if no break was hit. Dereferencing it (cur->page in this case) could load an out-of-bounds/undefined value making it unsafe to use that in the comparision to determine if the specific element was found. Since 'cur->page' *can* be out-ouf-bounds it cannot be guaranteed that by chance (or intention of an attacker) it matches the value of 'page' even though the correct element was not found. This is fixed by using a separate list iterator variable for the loop and only setting the original variable if a suitable element was found. Then determing if the element was found is simply checking if the variable is set. Fixes: 8c242db9b8c0 ("f2fs: fix stale ATOMIC_WRITTEN_PAGE private pointer") Signed-off-by: Jakob Koschel Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/segment.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 416d802ebbea..1b37a619065e 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -356,16 +356,19 @@ void f2fs_drop_inmem_page(struct inode *inode, struct page *page) struct f2fs_sb_info *sbi = F2FS_I_SB(inode); struct list_head *head = &fi->inmem_pages; struct inmem_pages *cur = NULL; + struct inmem_pages *tmp; f2fs_bug_on(sbi, !page_private_atomic(page)); mutex_lock(&fi->inmem_lock); - list_for_each_entry(cur, head, list) { - if (cur->page == page) + list_for_each_entry(tmp, head, list) { + if (tmp->page == page) { + cur = tmp; break; + } } - f2fs_bug_on(sbi, list_empty(head) || cur->page != page); + f2fs_bug_on(sbi, !cur); list_del(&cur->list); mutex_unlock(&fi->inmem_lock); -- 2.35.1