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 CB0BDC43334 for ; Thu, 23 Jun 2022 16:58:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233316AbiFWQ5n (ORCPT ); Thu, 23 Jun 2022 12:57:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233648AbiFWQvT (ORCPT ); Thu, 23 Jun 2022 12:51:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B93B50029; Thu, 23 Jun 2022 09:49:24 -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 4CF4561F99; Thu, 23 Jun 2022 16:49:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E9B2C3411B; Thu, 23 Jun 2022 16:49:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656002963; bh=5mbXSzNjpSRj9Uu7DEFHfMoAvquSppTKosRivKzhN5g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2ZEK6z8mAoWSSIr+bLIM09xmP7bDEMBulwXLf5RIXpo+IgtkCnER5ks9BvaGqDkc+ zxJ3wFlNZGPuXFEeGVCbRZ/e3omSqfVO54c4Ry9uBfprqbFOqJl4bu1wHy2F1k1Kf0 xSXpq4t2qSVvep81PVR2QgoV2bU1+/R0vDc9Mr0Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, kernel test robot , Theodore Tso , "Jason A. Donenfeld" Subject: [PATCH 4.9 043/264] random: fix soft lockup when trying to read from an uninitialized blocking pool Date: Thu, 23 Jun 2022 18:40:36 +0200 Message-Id: <20220623164345.287939032@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164344.053938039@linuxfoundation.org> References: <20220623164344.053938039@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: Theodore Ts'o commit 58be0106c5306b939b07b4b8bf00669a20593f4b upstream. Fixes: eb9d1bf079bb: "random: only read from /dev/random after its pool has received 128 bits" Reported-by: kernel test robot Signed-off-by: Theodore Ts'o Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -774,8 +774,11 @@ retry: if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; - if (has_initialized) + if (has_initialized) { r->initialized = 1; + wake_up_interruptible(&random_read_wait); + kill_fasync(&fasync, SIGIO, POLL_IN); + } trace_credit_entropy_bits(r->name, nbits, entropy_count >> ENTROPY_SHIFT, _RET_IP_); @@ -791,6 +794,13 @@ retry: entropy_bits = r->entropy_count >> ENTROPY_SHIFT; } + /* initialize the blocking pool if necessary */ + if (entropy_bits >= random_read_wakeup_bits && + !other->initialized) { + schedule_work(&other->push_work); + return; + } + /* should we wake readers? */ if (entropy_bits >= random_read_wakeup_bits && wq_has_sleeper(&random_read_wait)) { @@ -1992,8 +2002,8 @@ _random_read(int nonblock, char __user * return -EAGAIN; wait_event_interruptible(random_read_wait, - ENTROPY_BITS(&input_pool) >= - random_read_wakeup_bits); + blocking_pool.initialized && + (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)); if (signal_pending(current)) return -ERESTARTSYS; }