From nobody Mon Jun 29 12:39:15 2026 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 34804C433EF for ; Wed, 9 Feb 2022 18:59:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241685AbiBIS7L (ORCPT ); Wed, 9 Feb 2022 13:59:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241349AbiBIS50 (ORCPT ); Wed, 9 Feb 2022 13:57:26 -0500 Received: from isilmar-4.linta.de (isilmar-4.linta.de [136.243.71.142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 133E5C050CF6; Wed, 9 Feb 2022 10:57:24 -0800 (PST) X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from owl.dominikbrodowski.net (owl.brodo.linta [10.2.0.111]) by isilmar-4.linta.de (Postfix) with ESMTPSA id 850EB20140B; Wed, 9 Feb 2022 18:57:21 +0000 (UTC) Received: by owl.dominikbrodowski.net (Postfix, from userid 1000) id 6EB35803D6; Wed, 9 Feb 2022 19:57:06 +0100 (CET) Date: Wed, 9 Feb 2022 19:57:06 +0100 From: Dominik Brodowski To: "Jason A . Donenfeld" , tytso@mit.edu Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: [PATCH] random: fix locking for crng_init in crng_reseed() Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" crng_init is protected by primary_crng->lock. Therefore, we need to hold this lock when increasing crng_init to 2. As we shouldn't hold this lock for too long, only hold it for those parts which require protection. Signed-off-by: Dominik Brodowski --- drivers/char/random.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index cc4d9d414df2..aee56032ebb4 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -497,6 +497,7 @@ static void crng_slow_load(const void *cp, unsigned int= len) =20 static void crng_reseed(void) { + bool complete_init =3D false; unsigned long flags; int entropy_count; unsigned long next_gen; @@ -526,12 +527,14 @@ static void crng_reseed(void) ++next_gen; WRITE_ONCE(base_crng.generation, next_gen); base_crng.birth =3D jiffies; - spin_unlock_irqrestore(&base_crng.lock, flags); - memzero_explicit(key, sizeof(key)); - if (crng_init < 2) { invalidate_batched_entropy(); crng_init =3D 2; + complete_init =3D true; + } + spin_unlock_irqrestore(&base_crng.lock, flags); + memzero_explicit(key, sizeof(key)); + if (complete_init) { process_random_ready_list(); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN);