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 8B66BC433F5 for ; Fri, 27 May 2022 09:01:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349820AbiE0JBf (ORCPT ); Fri, 27 May 2022 05:01:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350518AbiE0JAD (ORCPT ); Fri, 27 May 2022 05:00:03 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 942F910274F; Fri, 27 May 2022 01:56:06 -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 ams.source.kernel.org (Postfix) with ESMTPS id D5D56B823D9; Fri, 27 May 2022 08:56:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEB60C34100; Fri, 27 May 2022 08:56:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653641763; bh=IRIB/nfddzpYszgOCi6TNfrnOf4M5Ta9hww7v3gomiQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0E4lgKzPGYrm4UkdSJEov2Dqdp2ww1OATHWGkcejLmZgi9mz0UE9nviL4SLxNvFvM IjxxDBLqnIhwnNBh1JliDO/Zn3Lmwwe8q3lEc9a5wum95/Je4LVq5FWDonGNub/B2+ 9+6yG35LkExw2M4crroccHfq17V0XtF6dNE6T1/E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Dominik Brodowski , Eric Biggers , "Jason A. Donenfeld" Subject: [PATCH 5.17 016/111] random: absorb fast pool into input pool after fast load Date: Fri, 27 May 2022 10:48:48 +0200 Message-Id: <20220527084821.509701521@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220527084819.133490171@linuxfoundation.org> References: <20220527084819.133490171@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Jason A. Donenfeld" commit c30c575db4858f0bbe5e315ff2e529c782f33a1f upstream. During crng_init == 0, we never credit entropy in add_interrupt_ randomness(), but instead dump it directly into the primary_crng. That's fine, except for the fact that we then wind up throwing away that entropy later when we switch to extracting from the input pool and xoring into (and later in this series overwriting) the primary_crng key. The two other early init sites -- add_hwgenerator_randomness()'s use crng_fast_load() and add_device_ randomness()'s use of crng_slow_load() -- always additionally give their inputs to the input pool. But not add_interrupt_randomness(). This commit fixes that shortcoming by calling mix_pool_bytes() after crng_fast_load() in add_interrupt_randomness(). That's partially verboten on PREEMPT_RT, where it implies taking spinlock_t from an IRQ handler. But this also only happens during early boot and then never again after that. Plus it's a trylock so it has the same considerations as calling crng_fast_load(), which we're already using. Cc: Theodore Ts'o Reviewed-by: Dominik Brodowski Reviewed-by: Eric Biggers Suggested-by: Eric Biggers Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -850,6 +850,10 @@ void add_interrupt_randomness(int irq) crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) { fast_pool->count = 0; fast_pool->last = now; + if (spin_trylock(&input_pool.lock)) { + _mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool)); + spin_unlock(&input_pool.lock); + } } return; }