From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934229AbbIVSc0 (ORCPT ); Tue, 22 Sep 2015 14:32:26 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42571 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759039AbbIVRx2 (ORCPT ); Tue, 22 Sep 2015 13:53:28 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= , David Vrabel , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 011/102] xen/gntdevt: Fix race condition in gntdev_release() Date: Tue, 22 Sep 2015 10:51:07 -0700 Message-Id: <1442944358-1248-12-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1442944358-1248-1-git-send-email-kamal@canonical.com> References: <1442944358-1248-1-git-send-email-kamal@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt7 -stable review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= commit 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 upstream. While gntdev_release() is called the MMU notifier is still registered and can traverse priv->maps list even if no pages are mapped (which is the case -- gntdev_release() is called after all). But gntdev_release() will clear that list, so make sure that only one of those things happens at the same time. Signed-off-by: Marek Marczykowski-Górecki Signed-off-by: David Vrabel Signed-off-by: Kamal Mostafa --- drivers/xen/gntdev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index b7f028a..91cc446 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -529,12 +529,14 @@ static int gntdev_release(struct inode *inode, struct file *flip) pr_debug("priv %p\n", priv); + mutex_lock(&priv->lock); while (!list_empty(&priv->maps)) { map = list_entry(priv->maps.next, struct grant_map, next); list_del(&map->next); gntdev_put_map(NULL /* already removed */, map); } WARN_ON(!list_empty(&priv->freeable_maps)); + mutex_unlock(&priv->lock); if (use_ptemod) mmu_notifier_unregister(&priv->mn, priv->mm); -- 1.9.1