From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:33912 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755962AbeD3T10 (ORCPT ); Mon, 30 Apr 2018 15:27:26 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleksandr Natalenko , Kees Cook , Jens Axboe Subject: [PATCH 4.14 57/91] bfq-iosched: ensure to clear bic/bfqq pointers when preparing request Date: Mon, 30 Apr 2018 12:24:39 -0700 Message-Id: <20180430184007.145652337@linuxfoundation.org> In-Reply-To: <20180430184004.216234025@linuxfoundation.org> References: <20180430184004.216234025@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe commit 72961c4e6082be79825265d9193272b8a1634dec upstream. Even if we don't have an IO context attached to a request, we still need to clear the priv[0..1] pointers, as they could be pointing to previously used bic/bfqq structures. If we don't do so, we'll either corrupt memory on dispatching a request, or cause an imbalance in counters. Inspired by a fix from Kees. Reported-by: Oleksandr Natalenko Reported-by: Kees Cook Cc: stable@vger.kernel.org Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/bfq-iosched.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4447,8 +4447,16 @@ static void bfq_prepare_request(struct r bool new_queue = false; bool bfqq_already_existing = false, split = false; - if (!rq->elv.icq) + /* + * Even if we don't have an icq attached, we should still clear + * the scheduler pointers, as they might point to previously + * allocated bic/bfqq structs. + */ + if (!rq->elv.icq) { + rq->elv.priv[0] = rq->elv.priv[1] = NULL; return; + } + bic = icq_to_bic(rq->elv.icq); spin_lock_irq(&bfqd->lock);