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 57FDFC433EF for ; Fri, 27 May 2022 11:52:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351688AbiE0Lwj (ORCPT ); Fri, 27 May 2022 07:52:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352241AbiE0LuO (ORCPT ); Fri, 27 May 2022 07:50:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0708B14D784; Fri, 27 May 2022 04:44:20 -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 804B5B8091D; Fri, 27 May 2022 11:44:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6813C385A9; Fri, 27 May 2022 11:44:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653651859; bh=IRIB/nfddzpYszgOCi6TNfrnOf4M5Ta9hww7v3gomiQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O1Z3D1L3k4Ori+qaiYYZOaqtlToc6GHt/jO2Go4Bl2ucPyeQmGyZ9RYHhLF7ziwXL X9Huk3esW777oKL68bGbJOj0DpD4pY1sPKYWoTO5ziJvTJu2T4D7eyMUFHs4j8F9Ka 5ePu03K2dzzdWJqopLoLTnotCs+8FsSbeF5YTzPA= 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 5.15 051/145] random: absorb fast pool into input pool after fast load Date: Fri, 27 May 2022 10:49:12 +0200 Message-Id: <20220527084856.956942421@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220527084850.364560116@linuxfoundation.org> References: <20220527084850.364560116@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; }