From patchwork Tue Sep 29 10:57:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 290962 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5876C47423 for ; Tue, 29 Sep 2020 12:06:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71D2020684 for ; Tue, 29 Sep 2020 12:06:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601381183; bh=rH+Ro2yxB1c3K2IWG3dLZLLOQ9cKHPpRcEWropz/1Mo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=InrpENaNhA5t1T6pWUDG6JDBA8+jRBXBgWhGGYVc7qibEOuvg8uk1IUSqPQ+ET/qY JlfAaSyPv0A5ltHP70w4UResx6GnXTzqn61CuDWosFeefQqaEEK6HKhQ2tnLiIyzUk MYHmiIhtUB+jkcjkCdXi5ty1+nTmZBj+nULibndA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730947AbgI2MGI (ORCPT ); Tue, 29 Sep 2020 08:06:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:54448 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730264AbgI2Lhh (ORCPT ); Tue, 29 Sep 2020 07:37:37 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E506723A77; Tue, 29 Sep 2020 11:36:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601379390; bh=rH+Ro2yxB1c3K2IWG3dLZLLOQ9cKHPpRcEWropz/1Mo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tc7IpMqaraYTyrrlEyh6fjmYOnhAXHKYEJuuSyqmOBwG2F0Ashd28wMmnPwVtg3M6 +tImYpevfIvH1HS/sqe2Ht/Na+87ahPBZrkHox/DcX4wzBK++ec4WnES/bw9BVM/6U G0rNY2rRlpf5veiAYq7hDhaXlTH87NWmJvOp/J5Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , Theodore Tso , Sasha Levin Subject: [PATCH 5.4 141/388] random: fix data races at timer_rand_state Date: Tue, 29 Sep 2020 12:57:52 +0200 Message-Id: <20200929110017.299454859@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929110010.467764689@linuxfoundation.org> References: <20200929110010.467764689@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qian Cai [ Upstream commit e00d996a4317aff5351c4338dd97d390225412c2 ] Fields in "struct timer_rand_state" could be accessed concurrently. Lockless plain reads and writes result in data races. Fix them by adding pairs of READ|WRITE_ONCE(). The data races were reported by KCSAN, BUG: KCSAN: data-race in add_timer_randomness / add_timer_randomness write to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 22: add_timer_randomness+0x100/0x190 add_timer_randomness at drivers/char/random.c:1152 add_disk_randomness+0x85/0x280 scsi_end_request+0x43a/0x4a0 scsi_io_completion+0xb7/0x7e0 scsi_finish_command+0x1ed/0x2a0 scsi_softirq_done+0x1c9/0x1d0 blk_done_softirq+0x181/0x1d0 __do_softirq+0xd9/0x57c irq_exit+0xa2/0xc0 do_IRQ+0x8b/0x190 ret_from_intr+0x0/0x42 cpuidle_enter_state+0x15e/0x980 cpuidle_enter+0x69/0xc0 call_cpuidle+0x23/0x40 do_idle+0x248/0x280 cpu_startup_entry+0x1d/0x1f start_secondary+0x1b2/0x230 secondary_startup_64+0xb6/0xc0 no locks held by swapper/22/0. irq event stamp: 32871382 _raw_spin_unlock_irqrestore+0x53/0x60 _raw_spin_lock_irqsave+0x21/0x60 _local_bh_enable+0x21/0x30 irq_exit+0xa2/0xc0 read to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 2: add_timer_randomness+0xe8/0x190 add_disk_randomness+0x85/0x280 scsi_end_request+0x43a/0x4a0 scsi_io_completion+0xb7/0x7e0 scsi_finish_command+0x1ed/0x2a0 scsi_softirq_done+0x1c9/0x1d0 blk_done_softirq+0x181/0x1d0 __do_softirq+0xd9/0x57c irq_exit+0xa2/0xc0 do_IRQ+0x8b/0x190 ret_from_intr+0x0/0x42 cpuidle_enter_state+0x15e/0x980 cpuidle_enter+0x69/0xc0 call_cpuidle+0x23/0x40 do_idle+0x248/0x280 cpu_startup_entry+0x1d/0x1f start_secondary+0x1b2/0x230 secondary_startup_64+0xb6/0xc0 no locks held by swapper/2/0. irq event stamp: 37846304 _raw_spin_unlock_irqrestore+0x53/0x60 _raw_spin_lock_irqsave+0x21/0x60 _local_bh_enable+0x21/0x30 irq_exit+0xa2/0xc0 Reported by Kernel Concurrency Sanitizer on: Hardware name: HP ProLiant BL660c Gen9, BIOS I38 10/17/2018 Link: https://lore.kernel.org/r/1582648024-13111-1-git-send-email-cai@lca.pw Signed-off-by: Qian Cai Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- drivers/char/random.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index e877c20e0ee02..75a8f7f572697 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1223,14 +1223,14 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num) * We take into account the first, second and third-order deltas * in order to make our estimate. */ - delta = sample.jiffies - state->last_time; - state->last_time = sample.jiffies; + delta = sample.jiffies - READ_ONCE(state->last_time); + WRITE_ONCE(state->last_time, sample.jiffies); - delta2 = delta - state->last_delta; - state->last_delta = delta; + delta2 = delta - READ_ONCE(state->last_delta); + WRITE_ONCE(state->last_delta, delta); - delta3 = delta2 - state->last_delta2; - state->last_delta2 = delta2; + delta3 = delta2 - READ_ONCE(state->last_delta2); + WRITE_ONCE(state->last_delta2, delta2); if (delta < 0) delta = -delta;