From patchwork Wed Mar 8 02:32:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13165141 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 109F9C678D5 for ; Wed, 8 Mar 2023 02:09:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229542AbjCHCJH (ORCPT ); Tue, 7 Mar 2023 21:09:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229582AbjCHCJF (ORCPT ); Tue, 7 Mar 2023 21:09:05 -0500 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A02C49CFD1; Tue, 7 Mar 2023 18:09:03 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4PWbMt5fNPz4f3nTX; Wed, 8 Mar 2023 10:08:58 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.127.227]) by APP3 (Coremail) with SMTP id _Ch0CgDHcyE47gdkBs8gEg--.52407S4; Wed, 08 Mar 2023 10:08:58 +0800 (CST) From: Yu Kuai To: jack@suse.cz, shinichiro.kawasaki@wdc.com, paolo.valente@linaro.org, axboe@kernel.dk, glusvardi@posteo.net, damien.lemoal@opensource.wdc.com, felicigb@gmail.com, inbox@emilianomaccaferri.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH] block, bfq: fix uaf for 'stable_merge_bfqq' Date: Wed, 8 Mar 2023 10:32:08 +0800 Message-Id: <20230308023208.379465-1-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <4e6e1606-1d9e-9903-8a44-ccac58a1fe06@kernel.dk> References: <4e6e1606-1d9e-9903-8a44-ccac58a1fe06@kernel.dk> MIME-Version: 1.0 X-CM-TRANSID: _Ch0CgDHcyE47gdkBs8gEg--.52407S4 X-Coremail-Antispam: 1UD129KBjvJXoW7Kr45XryUWF4kKry7Jr48Crg_yoW5JrWkpa 1DKw4avr1rJrW5XrWxAw40vF98tr43Ar9FyryrW347uw1DJrySvFsF9ayI9Fn2vr48CFnx Xw1qqas2kr48JrDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvY14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v2 6r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0J UdHUDUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Yu Kuai Before commit fd571df0ac5b ("block, bfq: turn bfqq_data into an array in bfq_io_cq"), process reference is read before bfq_put_stable_ref(), and it's safe if bfq_put_stable_ref() put the last reference, because process reference will be 0 and 'stable_merge_bfqq' won't be accessed in this case. However, the commit changed the order and will cause uaf for 'stable_merge_bfqq'. In order to emphasize that bfq_put_stable_ref() can drop the last reference, fix the problem by moving bfq_put_stable_ref() to the end of bfq_setup_stable_merge(). Fixes: fd571df0ac5b ("block, bfq: turn bfqq_data into an array in bfq_io_cq") Reported-and-tested-by: Shinichiro Kawasaki Link: https://lore.kernel.org/linux-block/20230307071448.rzihxbm4jhbf5krj@shindev/ Signed-off-by: Yu Kuai Reviewed-by: Jan Kara --- block/bfq-iosched.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 8a8d4441519c..d9ed3108c17a 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2854,11 +2854,11 @@ bfq_setup_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq, { int proc_ref = min(bfqq_process_refs(bfqq), bfqq_process_refs(stable_merge_bfqq)); - struct bfq_queue *new_bfqq; + struct bfq_queue *new_bfqq = NULL; - if (idling_boosts_thr_without_issues(bfqd, bfqq) || - proc_ref == 0) - return NULL; + bfqq_data->stable_merge_bfqq = NULL; + if (idling_boosts_thr_without_issues(bfqd, bfqq) || proc_ref == 0) + goto out; /* next function will take at least one ref */ new_bfqq = bfq_setup_merge(bfqq, stable_merge_bfqq); @@ -2873,6 +2873,11 @@ bfq_setup_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq, new_bfqq_data->stably_merged = true; } } + +out: + /* deschedule stable merge, because done or aborted here */ + bfq_put_stable_ref(stable_merge_bfqq); + return new_bfqq; } @@ -2933,11 +2938,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, struct bfq_queue *stable_merge_bfqq = bfqq_data->stable_merge_bfqq; - /* deschedule stable merge, because done or aborted here */ - bfq_put_stable_ref(stable_merge_bfqq); - - bfqq_data->stable_merge_bfqq = NULL; - return bfq_setup_stable_merge(bfqd, bfqq, stable_merge_bfqq, bfqq_data);