From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6DFCC10F14 for ; Thu, 3 Oct 2019 17:28:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D17320865 for ; Thu, 3 Oct 2019 17:28:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570123691; bh=UGqMufujAPeYf8XfJuRbDlboz+r/vDuLTwr5F1tDuSA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jTtSb8eF1q9XgVx+KwjUXonkr+mIGg7tc2wJYApIcQy21C3aWucsIGVjodQVY39bx km4YV3Gvw160GeiPo3GDpOg7tOHcSsdI8/t7U7zUuytNcIcpK05XAlaeJkMHCGFOp+ IYJEZDpGxjbtYkZepn4ael5VVo+ioiG7OwO5JK/w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388507AbfJCQOC (ORCPT ); Thu, 3 Oct 2019 12:14:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:37018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388488AbfJCQN7 (ORCPT ); Thu, 3 Oct 2019 12:13:59 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5DDF1222C2; Thu, 3 Oct 2019 16:13:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570119238; bh=UGqMufujAPeYf8XfJuRbDlboz+r/vDuLTwr5F1tDuSA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J7l5BQj4oUFFbp7+jtEcXcDohsnaGQaAECBoGrHBnbEj7GSqHkSgKu0skOlOmWZkg 8w08KqeKY7N+fZdgUiTFvEIRNM5nnrv/wNknVG3dkMhYhrG+XhC6CBTUhzg75x/CYc sIG9Eog4/cSx1SHMwySxXSUJinlQDy/qmxUWDA3A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Laurent Vivier , Theodore Tso , Herbert Xu Subject: [PATCH 4.14 178/185] hwrng: core - dont wait on add_early_randomness() Date: Thu, 3 Oct 2019 17:54:16 +0200 Message-Id: <20191003154521.457073485@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191003154437.541662648@linuxfoundation.org> References: <20191003154437.541662648@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Laurent Vivier commit 78887832e76541f77169a24ac238fccb51059b63 upstream. add_early_randomness() is called by hwrng_register() when the hardware is added. If this hardware and its module are present at boot, and if there is no data available the boot hangs until data are available and can't be interrupted. For instance, in the case of virtio-rng, in some cases the host can be not able to provide enough entropy for all the guests. We can have two easy ways to reproduce the problem but they rely on misconfiguration of the hypervisor or the egd daemon: - if virtio-rng device is configured to connect to the egd daemon of the host but when the virtio-rng driver asks for data the daemon is not connected, - if virtio-rng device is configured to connect to the egd daemon of the host but the egd daemon doesn't provide data. The guest kernel will hang at boot until the virtio-rng driver provides enough data. To avoid that, call rng_get_data() in non-blocking mode (wait=0) from add_early_randomness(). Signed-off-by: Laurent Vivier Fixes: d9e797261933 ("hwrng: add randomness to system from rng...") Cc: Reviewed-by: Theodore Ts'o Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- drivers/char/hw_random/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -67,7 +67,7 @@ static void add_early_randomness(struct size_t size = min_t(size_t, 16, rng_buffer_size()); mutex_lock(&reading_mutex); - bytes_read = rng_get_data(rng, rng_buffer, size, 1); + bytes_read = rng_get_data(rng, rng_buffer, size, 0); mutex_unlock(&reading_mutex); if (bytes_read > 0) add_device_randomness(rng_buffer, bytes_read);