From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758365AbbCDGOY (ORCPT ); Wed, 4 Mar 2015 01:14:24 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:41832 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758302AbbCDGOV (ORCPT ); Wed, 4 Mar 2015 01:14:21 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Konstantin Khlebnikov , Tejun Heo , Vivek Goyal , Jens Axboe Subject: [PATCH 3.10 29/53] cfq-iosched: handle failure of cfq group allocation Date: Tue, 3 Mar 2015 22:06:32 -0800 Message-Id: <20150304054614.804493821@linuxfoundation.org> X-Mailer: git-send-email 2.3.1 In-Reply-To: <20150304054609.869052846@linuxfoundation.org> References: <20150304054609.869052846@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 69abaffec7d47a083739b79e3066cb3730eba72e upstream. Cfq_lookup_create_cfqg() allocates struct blkcg_gq using GFP_ATOMIC. In cfq_find_alloc_queue() possible allocation failure is not handled. As a result kernel oopses on NULL pointer dereference when cfq_link_cfqq_cfqg() calls cfqg_get() for NULL pointer. Bug was introduced in v3.5 in commit cd1604fab4f9 ("blkcg: factor out blkio_group creation"). Prior to that commit cfq group lookup had returned pointer to root group as fallback. This patch handles this error using existing fallback oom_cfqq. Signed-off-by: Konstantin Khlebnikov Acked-by: Tejun Heo Acked-by: Vivek Goyal Fixes: cd1604fab4f9 ("blkcg: factor out blkio_group creation") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/cfq-iosched.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3575,6 +3575,11 @@ retry: blkcg = bio_blkcg(bio); cfqg = cfq_lookup_create_cfqg(cfqd, blkcg); + if (!cfqg) { + cfqq = &cfqd->oom_cfqq; + goto out; + } + cfqq = cic_to_cfqq(cic, is_sync); /* @@ -3611,7 +3616,7 @@ retry: } else cfqq = &cfqd->oom_cfqq; } - +out: if (new_cfqq) kmem_cache_free(cfq_pool, new_cfqq);