From patchwork Mon Jul 17 13:01:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Prasad Pandit X-Patchwork-Id: 9844897 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4A74C6037F for ; Mon, 17 Jul 2017 13:02:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3C82E2842E for ; Mon, 17 Jul 2017 13:02:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 312B62851D; Mon, 17 Jul 2017 13:02:50 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id A5B1E2850E for ; Mon, 17 Jul 2017 13:02:49 +0000 (UTC) Received: from localhost ([::1]:50264 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dX5fk-0004ak-Bm for patchwork-qemu-devel@patchwork.kernel.org; Mon, 17 Jul 2017 09:02:48 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35327) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dX5eo-0004X3-Ly for qemu-devel@nongnu.org; Mon, 17 Jul 2017 09:01:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dX5en-0000wC-AT for qemu-devel@nongnu.org; Mon, 17 Jul 2017 09:01:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64667) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dX5ee-0000uJ-Ey; Mon, 17 Jul 2017 09:01:40 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6D7872F86CE; Mon, 17 Jul 2017 13:01:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 6D7872F86CE Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=ppandit@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 6D7872F86CE Received: from localhost.localdomain (ovpn-116-83.sin2.redhat.com [10.67.116.83]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C3CC47E67F; Mon, 17 Jul 2017 13:01:33 +0000 (UTC) From: P J P To: Qemu Developers Date: Mon, 17 Jul 2017 18:31:30 +0530 Message-Id: <20170717130130.29211-1-ppandit@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 17 Jul 2017 13:01:39 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v1] ide: check BlockBackend object in ide_cancel_dma_sync X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Hajnoczi , John Snow , qemu-block@nongnu.org, Chensongnian , Prasad J Pandit Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Prasad J Pandit When cancelling pending DMA requests in ide_cancel_dma_sync, the s->blk object could be null, leading to a null dereference. Add check to avoid it. blk_bs (blk=0x0) at block/block-backend.c:389 blk_drain (blk=0x0) at block/block-backend.c:1232 ide_cancel_dma_sync (s=0x7f203241c1a8) at hw/ide/core.c:684 bmdma_cmd_writeb (bm=0x7f203241cf20, val=104) at hw/ide/pci.c:237 bmdma_write (opaque=0x7f203241cf20, addr=0, val=104, size=1) at hw/ide/piix.c:77 Reported-by: Chensongnian Signed-off-by: Prasad J Pandit --- hw/ide/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Update: add call stack trace leading the null dereference. diff --git a/hw/ide/core.c b/hw/ide/core.c index 0b48b64..04474b3 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -681,8 +681,10 @@ void ide_cancel_dma_sync(IDEState *s) #ifdef DEBUG_IDE printf("%s: draining all remaining requests", __func__); #endif - blk_drain(s->blk); - assert(s->bus->dma->aiocb == NULL); + if (s->blk) { + blk_drain(s->blk); + assert(s->bus->dma->aiocb == NULL); + } } }