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 8DFB2CCA47C for ; Tue, 7 Jun 2022 22:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383743AbiFGWIQ (ORCPT ); Tue, 7 Jun 2022 18:08:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379188AbiFGWG4 (ORCPT ); Tue, 7 Jun 2022 18:06:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF9B7252C39; Tue, 7 Jun 2022 12:15:54 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 4DFFE6192F; Tue, 7 Jun 2022 19:15:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52E99C385A2; Tue, 7 Jun 2022 19:15:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654629353; bh=4YDOMqXx4RcoErZe6jqiuMfx+Sf4E1czh/gF3x97jlY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XUDucJMhcbMuN3bxjprPrkgwsijJF5tUYiCgHw2KteGb/fPtoJxp6JFhMokXOvxTA JPVHLiYnlLGAoudeEp4m92urOJk/mr/1895bd+yYGoK90qTUPDvRUWQZEeM82WCbuT 1+CBn5P0LR4ye84jGi+Vq1IbB5mojbfwac5PWb5U= 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 5.18 660/879] f2fs: fix dereference of stale list iterator after loop body Date: Tue, 7 Jun 2022 19:02:58 +0200 Message-Id: <20220607165022.005037060@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607165002.659942637@linuxfoundation.org> References: <20220607165002.659942637@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: stable@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 bd9731cdec56..9dd9f88b75e9 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -355,16 +355,19 @@ 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