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Fri, 05 Mar 2021 11:56:21 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-212-nSDxR5OTNJitZN52Rs1f5A-1; Fri, 05 Mar 2021 11:55:55 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 59DCE18BEF9F; Fri, 5 Mar 2021 16:55:11 +0000 (UTC) Received: from merkur.redhat.com (ovpn-112-36.phx2.redhat.com [10.3.112.36]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C32B60BF3; Fri, 5 Mar 2021 16:55:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614963357; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3Z2AuwW/9GaMnMEUouEm1irTTlYSgTpDzabvvMAMFtI=; b=HNk9dnn4Nt332sl+YdEdx88PXwUxM5CpVVhAzdpB527Mlb2+ksjjWbk5sBHXoqcN4fe0z9 UDvZXXWbe0oDZepuymCvpKBnoNOIsqspPUEZtvMFp0Ntq5tyiUxaVRZT1imq1ftsYEJsMe 8ayjl+niQ+WcDmoGDVd58S67I7boOTk= X-MC-Unique: nSDxR5OTNJitZN52Rs1f5A-1 From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 03/31] backup-top: Refuse I/O in inactive state Date: Fri, 5 Mar 2021 17:54:26 +0100 Message-Id: <20210305165454.356840-4-kwolf@redhat.com> In-Reply-To: <20210305165454.356840-1-kwolf@redhat.com> References: <20210305165454.356840-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=63.128.21.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" From: Max Reitz When the backup-top node transitions from active to inactive in bdrv_backup_top_drop(), the BlockCopyState is freed and the filtered child is removed, so the node effectively becomes unusable. However, noone told its I/O functions this, so they will happily continue accessing bs->backing and s->bcs. Prevent that by aborting early when s->active is false. (After the preceding patch, the node should be gone after bdrv_backup_top_drop(), so this should largely be a theoretical problem. But still, better to be safe than sorry, and also I think it just makes sense to check s->active in the I/O functions.) Signed-off-by: Max Reitz Message-Id: <20210219153348.41861-3-mreitz@redhat.com> Signed-off-by: Kevin Wolf --- block/backup-top.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/block/backup-top.c b/block/backup-top.c index d1253e1aa6..589e8b651d 100644 --- a/block/backup-top.c +++ b/block/backup-top.c @@ -45,6 +45,12 @@ static coroutine_fn int backup_top_co_preadv( BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) { + BDRVBackupTopState *s =3D bs->opaque; + + if (!s->active) { + return -EIO; + } + return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); } =20 @@ -54,6 +60,10 @@ static coroutine_fn int backup_top_cbw(BlockDriverState = *bs, uint64_t offset, BDRVBackupTopState *s =3D bs->opaque; uint64_t off, end; =20 + if (!s->active) { + return -EIO; + } + if (flags & BDRV_REQ_WRITE_UNCHANGED) { return 0; } --=20 2.29.2