Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Cathy Avery , Konrad Rzeszutek Wilk Subject: [PATCH 4.1 56/86] xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing) Date: Fri, 6 Nov 2015 11:22:55 -0800 Message-Id: <20151106192208.140129002@linuxfoundation.org> In-Reply-To: <20151106192205.351595349@linuxfoundation.org> References: <20151106192205.351595349@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cathy Avery commit a54c8f0f2d7df525ff997e2afe71866a1a013064 upstream. xen-blkfront will crash if the check to talk_to_blkback() in blkback_changed()(XenbusStateInitWait) returns an error. The driver data is freed and info is set to NULL. Later during the close process via talk_to_blkback's call to xenbus_dev_fatal() the null pointer is passed to and dereference in blkfront_closing. Signed-off-by: Cathy Avery Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- drivers/block/xen-blkfront.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1925,7 +1925,8 @@ static void blkback_changed(struct xenbu break; /* Missed the backend's Closing state -- fallthrough */ case XenbusStateClosing: - blkfront_closing(info); + if (info) + blkfront_closing(info); break; } }