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 DD26FC433F5 for ; Mon, 24 Jan 2022 21:29:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352548AbiAXV3Z (ORCPT ); Mon, 24 Jan 2022 16:29:25 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:38842 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349609AbiAXVSG (ORCPT ); Mon, 24 Jan 2022 16:18:06 -0500 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 E0DDB614B8; Mon, 24 Jan 2022 21:18:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4075C340E4; Mon, 24 Jan 2022 21:18:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643059085; bh=NArxHwZeGD7GaMmhx/LlhECXgL7KMKQlYAHAYYPDj34=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K9rh77rzuFtCc0VgER0bo1cuClU1Y5l75TvX2G5oaWUWnxf9fTU3TfInc9WIigVMJ cD362BFh/A1DOIsgvDJ3MFOes02t2tCZmK9CFnCPbPB5w8ZbZiZ6baF/Id6Ah8Pvkm Lb8IiQt+0mvNerLPpGGCHXpm0E9NCSVgvLcUTjyg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Garry , Xiongfeng Wang , Robin Murphy , Joerg Roedel , Sasha Levin Subject: [PATCH 5.16 0499/1039] iommu/iova: Fix race between FQ timeout and teardown Date: Mon, 24 Jan 2022 19:38:08 +0100 Message-Id: <20220124184142.029731523@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184125.121143506@linuxfoundation.org> References: <20220124184125.121143506@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xiongfeng Wang [ Upstream commit d7061627d701c90e1cac1e1e60c45292f64f3470 ] It turns out to be possible for hotplugging out a device to reach the stage of tearing down the device's group and default domain before the domain's flush queue has drained naturally. At this point, it is then possible for the timeout to expire just before the del_timer() call in free_iova_flush_queue(), such that we then proceed to free the FQ resources while fq_flush_timeout() is still accessing them on another CPU. Crashes due to this have been observed in the wild while removing NVMe devices. Close the race window by using del_timer_sync() to safely wait for any active timeout handler to finish before we start to free things. We already avoid any locking in free_iova_flush_queue() since the FQ is supposed to be inactive anyway, so the potential deadlock scenario does not apply. Fixes: 9a005a800ae8 ("iommu/iova: Add flush timer") Reviewed-by: John Garry Signed-off-by: Xiongfeng Wang [ rm: rewrite commit message ] Signed-off-by: Robin Murphy Link: https://lore.kernel.org/r/0a365e5b07f14b7344677ad6a9a734966a8422ce.1639753638.git.robin.murphy@arm.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin --- drivers/iommu/iova.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 9e8bc802ac053..920fcc27c9a1e 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -83,8 +83,7 @@ static void free_iova_flush_queue(struct iova_domain *iovad) if (!has_iova_flush_queue(iovad)) return; - if (timer_pending(&iovad->fq_timer)) - del_timer(&iovad->fq_timer); + del_timer_sync(&iovad->fq_timer); fq_destroy_all_entries(iovad); -- 2.34.1