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 CAD31CCA483 for ; Tue, 7 Jun 2022 20:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358255AbiFGUAb (ORCPT ); Tue, 7 Jun 2022 16:00:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352980AbiFGSym (ORCPT ); Tue, 7 Jun 2022 14:54:42 -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 6258C14AF57; Tue, 7 Jun 2022 11:03:51 -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 1ABB0617AE; Tue, 7 Jun 2022 18:03:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8829BC36AFE; Tue, 7 Jun 2022 18:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654625030; bh=ggAdO0Ry7BMKXmTuMezMqaYPVCO6EkL3gl5dGlN1l4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mYzzqzK499ET1wsmZnghxVn+BkAe/pEDGWqy/W2I7xJEU5xqQJTla+lzq2EKr57+A xfVn7LLr5SIrULYwxNS4lAsc3WjKAodj/WkunfA5tGXKGD0K7WV5WpVrrMl38KSwCn EVZluW7AscXBLvNHYV1pC4S3olijG37G8o8qpjVC01WXFHIds1fLASG844w3/pz94t JrvU4AjGsLub/rMbcCrx0uPWzg6JWDeyBvT2Tfd84et5+bgKfoXW19ERZrdz7RulCC 71jG2j6EtE411PD0EDaSZaqbncwgjH1XWcHmbmNlScus+2x/Xffe/XDbZLFbI9xoGx EBEo9H5aqkCvg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Guoqing Jiang , Donald Buczek , Guoqing Jiang , Song Liu , Sasha Levin , linux-raid@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 15/19] md: protect md_unregister_thread from reentrancy Date: Tue, 7 Jun 2022 14:03:10 -0400 Message-Id: <20220607180317.482354-15-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220607180317.482354-1-sashal@kernel.org> References: <20220607180317.482354-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guoqing Jiang [ Upstream commit 1e267742283a4b5a8ca65755c44166be27e9aa0f ] Generally, the md_unregister_thread is called with reconfig_mutex, but raid_message in dm-raid doesn't hold reconfig_mutex to unregister thread, so md_unregister_thread can be called simulitaneously from two call sites in theory. Then after previous commit which remove the protection of reconfig_mutex for md_unregister_thread completely, the potential issue could be worse than before. Let's take pers_lock at the beginning of function to ensure reentrancy. Reported-by: Donald Buczek Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu Signed-off-by: Sasha Levin --- drivers/md/md.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 98c72dd56a2d..d2e2006ed792 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7252,17 +7252,22 @@ EXPORT_SYMBOL(md_register_thread); void md_unregister_thread(struct md_thread **threadp) { - struct md_thread *thread = *threadp; - if (!thread) - return; - pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk)); - /* Locking ensures that mddev_unlock does not wake_up a + struct md_thread *thread; + + /* + * Locking ensures that mddev_unlock does not wake_up a * non-existent thread */ spin_lock(&pers_lock); + thread = *threadp; + if (!thread) { + spin_unlock(&pers_lock); + return; + } *threadp = NULL; spin_unlock(&pers_lock); + pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk)); kthread_stop(thread->tsk); kfree(thread); } -- 2.35.1