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 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 40BA2C433E2 for ; Fri, 11 Sep 2020 17:24:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B215221E5 for ; Fri, 11 Sep 2020 17:24:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599845077; bh=TulE0s7oJnC/mvY51SC75yJFbCvnqjfF2xT7HJhRDWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=An01ukuZeP6+LHU4Euv1hls+paWMCzYKU9CByNJhdsUJprFN5xNrz4oZYVM4JQhre ucibmZ9dUPwucikxoCxnkuRemPabrs3323CTaNsxbKVYc8nO75ezR2X+PXOf9J/Y1M qA5pVePBpu29C9ZmdwcIZC3FJkrspMVaqicWwc3A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726363AbgIKRYd (ORCPT ); Fri, 11 Sep 2020 13:24:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:52806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726135AbgIKNAK (ORCPT ); Fri, 11 Sep 2020 09:00:10 -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 D31C92222A; Fri, 11 Sep 2020 12:56:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599828994; bh=TulE0s7oJnC/mvY51SC75yJFbCvnqjfF2xT7HJhRDWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZAascEWhZHYwSL/+oC3CiEJv79kONiOcD2KlgKg9ndLYdJuoXOqLAMmTLwxuJVQCk okbUl87+d3uj02rcf8b4cOWAK6fLclw1FfYWFo1A4z3yrjH2tFf9paPNCtDU210W8P kwhVpC7QR3Q3REkQO/IpH3ro3/RExysmmw7SQupQ= 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 4.9 24/71] fix regression in "epoll: Keep a reference on files added to the check list" Date: Fri, 11 Sep 2020 14:46:08 +0200 Message-Id: <20200911122506.144629368@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200911122504.928931589@linuxfoundation.org> References: <20200911122504.928931589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 aad52e1858363..8c40d6652a9a9 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1748,9 +1748,9 @@ 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); } } } -- 2.25.1