From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030339AbcIVRoZ (ORCPT ); Thu, 22 Sep 2016 13:44:25 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57057 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965416AbcIVRoT (ORCPT ); Thu, 22 Sep 2016 13:44:19 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Devesh Sharma , Jason Gunthorpe , Yishai Hadas , Leon Romanovsky , Doug Ledford Subject: [PATCH 4.7 058/184] IB/uverbs: Fix race between uverbs_close and remove_one Date: Thu, 22 Sep 2016 19:39:52 +0200 Message-Id: <20160922174051.189820771@linuxfoundation.org> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20160922174048.653794923@linuxfoundation.org> References: <20160922174048.653794923@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Gunthorpe commit d1e09f304a1d9651c5059ebfeb696dc2effc9b32 upstream. Fixes an oops that might happen if uverbs_close races with remove_one. Both contexts may run ib_uverbs_cleanup_ucontext, it depends on the flow. Currently, there is no protection for a case that remove_one didn't make the cleanup it runs to its end, the underlying ib_device was freed then uverbs_close will call ib_uverbs_cleanup_ucontext and OOPs. Above might happen if uverbs_close deleted the file from the list then remove_one didn't find it and runs to its end. Fixes to protect against that case by a new cleanup lock so that ib_uverbs_cleanup_ucontext will be called always before that remove_one is ended. Fixes: 35d4a0b63dc0 ("IB/uverbs: Fix race between ib_uverbs_open and remove_one") Reported-by: Devesh Sharma Signed-off-by: Jason Gunthorpe Signed-off-by: Yishai Hadas Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/uverbs.h | 1 drivers/infiniband/core/uverbs_main.c | 37 ++++++++++++++++++++++------------ 2 files changed, 25 insertions(+), 13 deletions(-) --- a/drivers/infiniband/core/uverbs.h +++ b/drivers/infiniband/core/uverbs.h @@ -116,6 +116,7 @@ struct ib_uverbs_event_file { struct ib_uverbs_file { struct kref ref; struct mutex mutex; + struct mutex cleanup_mutex; /* protect cleanup */ struct ib_uverbs_device *device; struct ib_ucontext *ucontext; struct ib_event_handler event_handler; --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -931,6 +931,7 @@ static int ib_uverbs_open(struct inode * file->async_file = NULL; kref_init(&file->ref); mutex_init(&file->mutex); + mutex_init(&file->cleanup_mutex); filp->private_data = file; kobject_get(&dev->kobj); @@ -956,18 +957,20 @@ static int ib_uverbs_close(struct inode { struct ib_uverbs_file *file = filp->private_data; struct ib_uverbs_device *dev = file->device; - struct ib_ucontext *ucontext = NULL; + + mutex_lock(&file->cleanup_mutex); + if (file->ucontext) { + ib_uverbs_cleanup_ucontext(file, file->ucontext); + file->ucontext = NULL; + } + mutex_unlock(&file->cleanup_mutex); mutex_lock(&file->device->lists_mutex); - ucontext = file->ucontext; - file->ucontext = NULL; if (!file->is_closed) { list_del(&file->list); file->is_closed = 1; } mutex_unlock(&file->device->lists_mutex); - if (ucontext) - ib_uverbs_cleanup_ucontext(file, ucontext); if (file->async_file) kref_put(&file->async_file->ref, ib_uverbs_release_event_file); @@ -1181,22 +1184,30 @@ static void ib_uverbs_free_hw_resources( mutex_lock(&uverbs_dev->lists_mutex); while (!list_empty(&uverbs_dev->uverbs_file_list)) { struct ib_ucontext *ucontext; - file = list_first_entry(&uverbs_dev->uverbs_file_list, struct ib_uverbs_file, list); file->is_closed = 1; - ucontext = file->ucontext; list_del(&file->list); - file->ucontext = NULL; kref_get(&file->ref); mutex_unlock(&uverbs_dev->lists_mutex); - /* We must release the mutex before going ahead and calling - * disassociate_ucontext. disassociate_ucontext might end up - * indirectly calling uverbs_close, for example due to freeing - * the resources (e.g mmput). - */ + ib_uverbs_event_handler(&file->event_handler, &event); + + mutex_lock(&file->cleanup_mutex); + ucontext = file->ucontext; + file->ucontext = NULL; + mutex_unlock(&file->cleanup_mutex); + + /* At this point ib_uverbs_close cannot be running + * ib_uverbs_cleanup_ucontext + */ if (ucontext) { + /* We must release the mutex before going ahead and + * calling disassociate_ucontext. disassociate_ucontext + * might end up indirectly calling uverbs_close, + * for example due to freeing the resources + * (e.g mmput). + */ ib_dev->disassociate_ucontext(ucontext); ib_uverbs_cleanup_ucontext(file, ucontext); }