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 87763CCA48F for ; Tue, 7 Jun 2022 19:42:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357147AbiFGTlV (ORCPT ); Tue, 7 Jun 2022 15:41:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354432AbiFGSrC (ORCPT ); Tue, 7 Jun 2022 14:47:02 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7382044A24; Tue, 7 Jun 2022 11:01:12 -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 ams.source.kernel.org (Postfix) with ESMTPS id 226FBB82239; Tue, 7 Jun 2022 18:01:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9F99C385A5; Tue, 7 Jun 2022 18:01:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654624869; bh=IdSUre7wjAX46gQRG26H7jmloFAMbUDPlBP85FdpWYA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E5SRhMNxcuAuTfK2l/KA47Ulip72CR0GXTWnY2biXyW6+N7HH8MuoEzkt8DAaKgEJ wf0NW4gEWGRLI/25Re6nATUqcPlNx8bFerzH/luzjz7B4Lxibk7FlSwYto6/GMK9kc gxDKcTRcd7nC3fsX7H3DdH14h9wA5WSlZRMhv5tkoVync0djlhrqWDakgufiYxP9vV C2mElKu2/qmjPxIAgIdiQMUTa0vZnzmPPh1v0P0COuMwZBisakBdwfHbXRqk6mX6b7 f7EwNpgKL5Rp+TxhQslIlJwk6PvST+9yX6Ow3nHmdJPtNWSGm7ZeaxPn7pTlcF2v3q h1eItGwaKboVQ== 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 5.4 22/34] md: protect md_unregister_thread from reentrancy Date: Tue, 7 Jun 2022 13:59:57 -0400 Message-Id: <20220607180011.481266-22-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220607180011.481266-1-sashal@kernel.org> References: <20220607180011.481266-1-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 25c51746957f..29ed9b754d1d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7775,17 +7775,22 @@ 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