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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6993C433FE for ; Thu, 13 Oct 2022 16:19:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229614AbiJMQT2 (ORCPT ); Thu, 13 Oct 2022 12:19:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229772AbiJMQT1 (ORCPT ); Thu, 13 Oct 2022 12:19:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F00191382D6 for ; Thu, 13 Oct 2022 09:19:26 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8C8816173A for ; Thu, 13 Oct 2022 16:19:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CD65C433D6; Thu, 13 Oct 2022 16:19:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1665677966; bh=9unufc0GmS0V4TPu72uaUpjrVNPAcjjbH6GrMX5K4m4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vVqbxYPbYWewMQXWvcIUQ+JCBIBLGarNJF25Xx086TrtPfV6L9rsswHoU+VVu8FNC Wigs+DDMRZkk5C3pk/8eVzlkqIFeHhLZ3aHoU5ca0TaHEe8aqdBNJGiYW2xmUq93kG TPu7kUO4IwaCj0HI5iTT/ChZL5sk4Wqg9o6GJlBI= Date: Thu, 13 Oct 2022 18:20:10 +0200 From: Greg KH To: "Jason A. Donenfeld" Cc: stable@vger.kernel.org Subject: Re: [PATCH stable 1/3] random: restore O_NONBLOCK support Message-ID: References: <20221013153654.1397691-1-Jason@zx2c4.com> <20221013153654.1397691-2-Jason@zx2c4.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20221013153654.1397691-2-Jason@zx2c4.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Oct 13, 2022 at 09:36:52AM -0600, Jason A. Donenfeld wrote: > commit cd4f24ae9404fd31fc461066e57889be3b68641b upstream. > > Prior to 5.6, when /dev/random was opened with O_NONBLOCK, it would > return -EAGAIN if there was no entropy. When the pools were unified in > 5.6, this was lost. The post 5.6 behavior of blocking until the pool is > initialized, and ignoring O_NONBLOCK in the process, went unnoticed, > with no reports about the regression received for two and a half years. > However, eventually this indeed did break somebody's userspace. > > So we restore the old behavior, by returning -EAGAIN if the pool is not > initialized. Unlike the old /dev/random, this can only occur during > early boot, after which it never blocks again. > > In order to make this O_NONBLOCK behavior consistent with other > expectations, also respect users reading with preadv2(RWF_NOWAIT) and > similar. > > Fixes: 30c08efec888 ("random: make /dev/random be almost like /dev/urandom") > Reported-by: Guozihua > Reported-by: Zhongguohua > Cc: Al Viro > Cc: Theodore Ts'o > Cc: Andrew Lutomirski > Cc: stable@vger.kernel.org > Signed-off-by: Jason A. Donenfeld > --- > drivers/char/mem.c | 4 ++-- > drivers/char/random.c | 5 +++++ > 2 files changed, 7 insertions(+), 2 deletions(-) Still breaks on older kernels: drivers/char/random.c: In function ‘random_read_iter’: drivers/char/random.c:1299:33: error: ‘IOCB_NOWAIT’ undeclared (first use in this function); did you mean ‘IPC_NOWAIT’? 1299 | ((kiocb->ki_flags & IOCB_NOWAIT) || | ^~~~~~~~~~~ | IPC_NOWAIT drivers/char/random.c:1299:33: note: each undeclared identifier is reported only once for each function it appears in drivers/char/mem.c:872:48: error: ‘FMODE_NOWAIT’ undeclared here (not in a function); did you mean ‘FOLL_NOWAIT’? 872 | [8] = { "random", 0666, &random_fops, FMODE_NOWAIT }, | ^~~~~~~~~~~~ | FOLL_NOWAIT