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 D9B53C433FE for ; Fri, 27 May 2022 08:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349621AbiE0I5w (ORCPT ); Fri, 27 May 2022 04:57:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350369AbiE0IzS (ORCPT ); Fri, 27 May 2022 04:55:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96C10106A44; Fri, 27 May 2022 01:53:44 -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 E993D61D54; Fri, 27 May 2022 08:53:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91E1DC385A9; Fri, 27 May 2022 08:53:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653641623; bh=/taNfpjeICuWWVktR629JPn5TweCvJIQlqTEdvykcDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lLSqcDLFnlHdAywpT1ZdmUxPZTtu2Kdtnuku60PPS8dC7U7IlZN3vbqdxLF6eG9il uJK94uDmU67yaLZH+9hMSQYH+i5Aa+1Fp5CgtWK1/L8+LY6DgpPXmpAKv3dw78kafC b69hbMsUOo3RDO+I4fqTlyAuPuaJ8sb32kS13emo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dominik Brodowski , Eric Biggers , "Jason A. Donenfeld" Subject: [PATCH 5.17 010/111] random: fix locking in crng_fast_load() Date: Fri, 27 May 2022 10:48:42 +0200 Message-Id: <20220527084820.568796827@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: linux-kernel@vger.kernel.org From: Dominik Brodowski commit 7c2fe2b32bf76441ff5b7a425b384e5f75aa530a upstream. crng_init is protected by primary_crng->lock, so keep holding that lock when incrementing crng_init from 0 to 1 in crng_fast_load(). The call to pr_notice() can wait until the lock is released; this code path cannot be reached twice, as crng_fast_load() aborts early if crng_init > 0. Signed-off-by: Dominik Brodowski Reviewed-by: Eric Biggers Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -647,12 +647,13 @@ static size_t crng_fast_load(const u8 *c p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp; cp++; crng_init_cnt++; len--; ret++; } - spin_unlock_irqrestore(&primary_crng.lock, flags); if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { invalidate_batched_entropy(); crng_init = 1; - pr_notice("fast init done\n"); } + spin_unlock_irqrestore(&primary_crng.lock, flags); + if (crng_init == 1) + pr_notice("fast init done\n"); return ret; }