Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938830AbcKNCkw (ORCPT ); Sun, 13 Nov 2016 21:40:52 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:47349 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938676AbcKNCde (ORCPT ); Sun, 13 Nov 2016 21:33:34 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David Vrabel" , "Ed Swierk" , "Jan Beulich" , "Jan Beulich" Date: Mon, 14 Nov 2016 00:14:07 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 150/152] xenbus: don't BUG() on user mode induced condition In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1681 Lines: 57 3.2.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jan Beulich commit 0beef634b86a1350c31da5fcc2992f0d7c8a622b upstream. Inability to locate a user mode specified transaction ID should not lead to a kernel crash. For other than XS_TRANSACTION_START also don't issue anything to xenbus if the specified ID doesn't match that of any active transaction. Signed-off-by: Jan Beulich Signed-off-by: David Vrabel Cc: Ed Swierk [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/xen/xenfs/xenbus.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/drivers/xen/xenfs/xenbus.c +++ b/drivers/xen/xenfs/xenbus.c @@ -310,11 +310,18 @@ static int xenbus_write_transaction(unsi rc = -ENOMEM; goto out; } + } else { + list_for_each_entry(trans, &u->transactions, list) + if (trans->handle.id == u->u.msg.tx_id) + break; + if (&trans->list == &u->transactions) + return -ESRCH; } reply = xenbus_dev_request_and_reply(&u->u.msg); if (IS_ERR(reply)) { - kfree(trans); + if (msg_type == XS_TRANSACTION_START) + kfree(trans); rc = PTR_ERR(reply); goto out; } @@ -324,12 +331,7 @@ static int xenbus_write_transaction(unsi list_add(&trans->list, &u->transactions); } else if (msg_type == XS_TRANSACTION_END) { - list_for_each_entry(trans, &u->transactions, list) - if (trans->handle.id == u->u.msg.tx_id) - break; - BUG_ON(&trans->list == &u->transactions); list_del(&trans->list); - kfree(trans); }