From patchwork Tue Sep 8 15:25:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 309977 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F9B3C433E2 for ; Tue, 8 Sep 2020 18:37:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 568502080C for ; Tue, 8 Sep 2020 18:37:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599590263; bh=DRykGmsrhDO0Us782MSpcBi89Hw7gBTfUHhvyx/t8kE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UXTTM5f2OaaOMsGKVuY/V4fDyGpzCr4U4x4xlnOXZRfX/7suKjpBLLvp3kt+bDJZy 6azKqzncfrDCDaAUK1q51D4pMRPSInXDM/ZH1rNMgmjirhflI76uUl5jmjH8WFS/yT Q46jbSZh8+6yfpQJjZtzA+5v+S4CQ54L0/Mvdits= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729298AbgIHShm (ORCPT ); Tue, 8 Sep 2020 14:37:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:53450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731337AbgIHQJA (ORCPT ); Tue, 8 Sep 2020 12:09:00 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1EF592410A; Tue, 8 Sep 2020 15:48:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599580136; bh=DRykGmsrhDO0Us782MSpcBi89Hw7gBTfUHhvyx/t8kE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2vmnP4lhWZey9GEpCUGjGoCZicMAmUC0bp5wGKAD9Bmpzh/gwWF2zVJ19SUFbIBdf /Ei6ZbhElm6wrr9MlktVGISmCuuBVlpqk3m4p5qEwp5/Sb1hy1DYrVduor3OFOv5+O InWZu2+EndBqzPoM++56W55uhjiqYbgGr2n/BpUQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Marc Zyngier , Al Viro , Sasha Levin Subject: [PATCH 4.19 42/88] fix regression in "epoll: Keep a reference on files added to the check list" Date: Tue, 8 Sep 2020 17:25:43 +0200 Message-Id: <20200908152223.227588536@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152221.082184905@linuxfoundation.org> References: <20200908152221.082184905@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Al Viro [ Upstream commit 77f4689de17c0887775bb77896f4cc11a39bf848 ] epoll_loop_check_proc() can run into a file already committed to destruction; we can't grab a reference on those and don't need to add them to the set for reverse path check anyway. Tested-by: Marc Zyngier Fixes: a9ed4a6560b8 ("epoll: Keep a reference on files added to the check list") Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/eventpoll.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index f988ccd064a22..61a52bb26d127 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1891,9 +1891,9 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) * during ep_insert(). */ if (list_empty(&epi->ffd.file->f_tfile_llink)) { - get_file(epi->ffd.file); - list_add(&epi->ffd.file->f_tfile_llink, - &tfile_check_list); + if (get_file_rcu(epi->ffd.file)) + list_add(&epi->ffd.file->f_tfile_llink, + &tfile_check_list); } } }