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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 28473C43381 for ; Tue, 26 Mar 2019 01:40:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E094D2083D for ; Tue, 26 Mar 2019 01:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730906AbfCZBkn (ORCPT ); Mon, 25 Mar 2019 21:40:43 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:58644 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727506AbfCZBkm (ORCPT ); Mon, 25 Mar 2019 21:40:42 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1h8b4x-0004Yr-0Z; Tue, 26 Mar 2019 01:40:39 +0000 Date: Tue, 26 Mar 2019 01:40:38 +0000 From: Al Viro To: Linus Torvalds Cc: syzbot , Alexei Starovoitov , Daniel Borkmann , linux-fsdevel , Linux List Kernel Mailing , syzkaller-bugs Subject: ubifs: fix use-after-free on symlink traversal Message-ID: <20190326014038.GW2217@ZenIV.linux.org.uk> References: <0000000000006946d2057bbd0eef@google.com> <20190325045744.GK2217@ZenIV.linux.org.uk> <20190325211405.GP2217@ZenIV.linux.org.uk> <20190325233731.GS2217@ZenIV.linux.org.uk> <20190326013858.GU2217@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190326013858.GU2217@ZenIV.linux.org.uk> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org free the symlink body after the same RCU delay we have for freeing the struct inode itself, so that traversal during RCU pathwalk wouldn't step into freed memory. Signed-off-by: Al Viro --- diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 8dc2818fdd84..12628184772c 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -276,14 +276,12 @@ static void ubifs_i_callback(struct rcu_head *head) { struct inode *inode = container_of(head, struct inode, i_rcu); struct ubifs_inode *ui = ubifs_inode(inode); + kfree(ui->data); kmem_cache_free(ubifs_inode_slab, ui); } static void ubifs_destroy_inode(struct inode *inode) { - struct ubifs_inode *ui = ubifs_inode(inode); - - kfree(ui->data); call_rcu(&inode->i_rcu, ubifs_i_callback); }