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 4E3A2EB64DA for ; Sun, 2 Jul 2023 19:44:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232476AbjGBToa (ORCPT ); Sun, 2 Jul 2023 15:44:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232124AbjGBTnK (ORCPT ); Sun, 2 Jul 2023 15:43:10 -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 43AD42695; Sun, 2 Jul 2023 12:42:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4485960CBB; Sun, 2 Jul 2023 19:40:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9007C433CA; Sun, 2 Jul 2023 19:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688326843; bh=+fWCUl+j6Cp2TLiSq1tE+s2/tOafQ4TY0PboIMouVao=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SanmETBGG4c6EK0uGdVN0YlRUH9jWAEDSLPBUSWfT6OJ1gLOvhl2l5CsG/4f6uwY5 iTJoF2Syeax/wFqXxCV7uKSFGoDFIN4VTERMnuS2+u/bJOECGgcNAmwV7Cq4b/4ScS RUOvGKSzzIk9dIZXcbQNxwYaBwYR+3laeWRAOAmmQKqeH+Vu3Qx8lWs7rEDeQ2QhWw XExhcFp8gjozhDCwvc0VCA7RakVD4y0PR0JXlbF3rGnENKc7Mo16SsWsn8ucCVmnlm oPDCFkpyol0osNiwkffLWVAfA8dGC/gXK4RPlKZ1WBhoczlYIzMi0IVEZ58jCFyl4z a3tMhpyk+AVOg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ming Lei , Guangwu Zhang , Jens Axboe , Sasha Levin , linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 6.4 10/15] blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none Date: Sun, 2 Jul 2023 15:40:15 -0400 Message-Id: <20230702194020.1776895-10-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230702194020.1776895-1-sashal@kernel.org> References: <20230702194020.1776895-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.4.1 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ming Lei [ Upstream commit 245165658e1c9f95c0fecfe02b9b1ebd30a1198a ] After grabbing q->sysfs_lock, q->elevator may become NULL because of elevator switch. Fix the NULL dereference on q->elevator by checking it with lock. Reported-by: Guangwu Zhang Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20230616132354.415109-1-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-mq.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 850bfb844ed2f..9516f65a50ea4 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4608,9 +4608,6 @@ static bool blk_mq_elv_switch_none(struct list_head *head, { struct blk_mq_qe_pair *qe; - if (!q->elevator) - return true; - qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY); if (!qe) return false; @@ -4618,6 +4615,12 @@ static bool blk_mq_elv_switch_none(struct list_head *head, /* q->elevator needs protection from ->sysfs_lock */ mutex_lock(&q->sysfs_lock); + /* the check has to be done with holding sysfs_lock */ + if (!q->elevator) { + kfree(qe); + goto unlock; + } + INIT_LIST_HEAD(&qe->node); qe->q = q; qe->type = q->elevator->type; @@ -4625,6 +4628,7 @@ static bool blk_mq_elv_switch_none(struct list_head *head, __elevator_get(qe->type); list_add(&qe->node, head); elevator_disable(q); +unlock: mutex_unlock(&q->sysfs_lock); return true; -- 2.39.2