From patchwork Tue Sep 8 15:23:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 264176 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 9324DC433E2 for ; Tue, 8 Sep 2020 19:21:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5220420759 for ; Tue, 8 Sep 2020 19:21:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599592914; bh=HdHRm4k1Unbl63MLg8T1pZK1Y+sHxgKhhFb6EWvWNXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=m0BwxcgaQYa9EyXb4Qx0ScwoNpcj+ftSmJ5iAjN21Fj9q9+yZ3kOL9QqEX8ONzDIr QsNISkPYqUsdT8DK8FtpNZLV52j20Yc65L4+TILrqalj9/FRMrqIsYO3Y5chCZvU56 WwpbHXbkmYgkv+BjyNLjXDCruPMAGHzYR81BGeZo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730532AbgIHTVt (ORCPT ); Tue, 8 Sep 2020 15:21:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:51456 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731107AbgIHQBm (ORCPT ); Tue, 8 Sep 2020 12:01:42 -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 3B3C123F2A; Tue, 8 Sep 2020 15:38:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599579482; bh=HdHRm4k1Unbl63MLg8T1pZK1Y+sHxgKhhFb6EWvWNXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dcUDEq1nLBjxNgqS/7x8c9Eu+/f9dhtVFo5xbsz7/TH+AgnJPAjEJr32lze9yLrid CK9ThfhIDkirqrI8lONXritzwvNt8Wc4wmpydc7HH0DZkeBZy2SYNG7y+I0rUKkUxp 4Le8zOxaZl0cRxOzNmwiiC9SLVFkgTtwGYc0lowc= 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 5.8 096/186] fix regression in "epoll: Keep a reference on files added to the check list" Date: Tue, 8 Sep 2020 17:23:58 +0200 Message-Id: <20200908152246.285858895@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152241.646390211@linuxfoundation.org> References: <20200908152241.646390211@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 e0decff22ae27..8107e06d7f6f5 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1995,9 +1995,9 @@ 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); } } }