From patchwork Tue Jan 15 15:47:24 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Cody X-Patchwork-Id: 212215 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 135362C00A7 for ; Wed, 16 Jan 2013 03:06:27 +1100 (EST) Received: from localhost ([::1]:50456 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tv91t-00012j-4y for incoming@patchwork.ozlabs.org; Tue, 15 Jan 2013 11:06:25 -0500 Received: from eggs.gnu.org ([208.118.235.92]:50179) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tv91e-00012d-Qe for qemu-devel@nongnu.org; Tue, 15 Jan 2013 11:06:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tv91c-0000vR-BA for qemu-devel@nongnu.org; Tue, 15 Jan 2013 11:06:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51525) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tv8jY-00048z-LV for qemu-devel@nongnu.org; Tue, 15 Jan 2013 10:47:28 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r0FFlQCL007292 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 15 Jan 2013 10:47:26 -0500 Received: from localhost (ovpn-112-44.phx2.redhat.com [10.3.112.44]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r0FFlOdB018774 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 15 Jan 2013 10:47:26 -0500 From: Jeff Cody To: qemu-devel@nongnu.org Date: Tue, 15 Jan 2013 10:47:24 -0500 Message-Id: <82f8ffaa908befab90470a79e0feb105af9aad84.1358264426.git.jcody@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, armbru@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH] block: fix null-pointer bug on error case in block commit X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org This is a bug that was caught by a coverity run by Markus. In the error case when we errored out to exit_restore_open early in the function, 'overlay_bs' was still NULL at that point, although it is used to look up flags and perform a bdrv_reopen(). Move the overlay_bs lookup to where it is needed, and check for NULL before restoring the flags. Also get rid of the unneeded parameter initialization. Reported-By: Markus Armbruster Signed-off-by: Jeff Cody Reviewed-by: Markus Armbruster --- block/commit.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/block/commit.c b/block/commit.c index 61ebdba..553447e 100644 --- a/block/commit.c +++ b/block/commit.c @@ -65,7 +65,7 @@ static void coroutine_fn commit_run(void *opaque) BlockDriverState *active = s->active; BlockDriverState *top = s->top; BlockDriverState *base = s->base; - BlockDriverState *overlay_bs = NULL; + BlockDriverState *overlay_bs; int64_t sector_num, end; int ret = 0; int n = 0; @@ -92,8 +92,6 @@ static void coroutine_fn commit_run(void *opaque) } } - overlay_bs = bdrv_find_overlay(active, top); - end = s->common.len >> BDRV_SECTOR_BITS; buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE); @@ -156,7 +154,8 @@ exit_restore_reopen: if (s->base_flags != bdrv_get_flags(base)) { bdrv_reopen(base, s->base_flags, NULL); } - if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { + overlay_bs = bdrv_find_overlay(active, top); + if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL); }