Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753876AbcDRKzz (ORCPT ); Mon, 18 Apr 2016 06:55:55 -0400 Received: from mail.kernel.org ([198.145.29.136]:35463 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752862AbcDRKvO (ORCPT ); Mon, 18 Apr 2016 06:51:14 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Cathy Avery , Konrad Rzeszutek Wilk , Zefan Li Subject: [PATCH 3.4 76/92] xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing) Date: Mon, 18 Apr 2016 18:46:21 +0800 Message-Id: <1460976397-5688-76-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1460976338-5631-1-git-send-email-lizf@kernel.org> References: <1460976338-5631-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1210 Lines: 38 From: Cathy Avery 3.4.112-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: Zefan Li --- drivers/block/xen-blkfront.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index a81cdd7..16477b2 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1314,7 +1314,8 @@ static void blkback_changed(struct xenbus_device *dev, break; /* Missed the backend's Closing state -- fallthrough */ case XenbusStateClosing: - blkfront_closing(info); + if (info) + blkfront_closing(info); break; } } -- 1.9.1