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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 21538C433E0 for ; Mon, 4 Jan 2021 07:32:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF3492228A for ; Mon, 4 Jan 2021 07:32:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727357AbhADHcH (ORCPT ); Mon, 4 Jan 2021 02:32:07 -0500 Received: from relay-us1.mymailcheap.com ([51.81.35.219]:33680 "EHLO relay-us1.mymailcheap.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727156AbhADHcG (ORCPT ); Mon, 4 Jan 2021 02:32:06 -0500 Received: from relay5.mymailcheap.com (relay5.mymailcheap.com [159.100.248.207]) by relay-us1.mymailcheap.com (Postfix) with ESMTPS id 4116720E62 for ; Mon, 4 Jan 2021 07:31:25 +0000 (UTC) Received: from relay3.mymailcheap.com (relay3.mymailcheap.com [217.182.119.155]) by relay5.mymailcheap.com (Postfix) with ESMTPS id 127D2260EC; Mon, 4 Jan 2021 07:30:31 +0000 (UTC) Received: from filter2.mymailcheap.com (filter2.mymailcheap.com [91.134.140.82]) by relay3.mymailcheap.com (Postfix) with ESMTPS id EFBA83F15F; Mon, 4 Jan 2021 08:28:55 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by filter2.mymailcheap.com (Postfix) with ESMTP id B6B702A7E5; Mon, 4 Jan 2021 08:28:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mymailcheap.com; s=default; t=1609745335; bh=ubj56mHRi69L846UzsE9e5xddidrKAo6HI48wtk8xJs=; h=From:To:Cc:Subject:Date:From; b=jyaTz//wcctD90WKXit3aBiUODYu96r27d540jeX1HUmpQOTQjCeDgF4k1Av+zhCI 9k+W3oVB4Lz/x425zj0thC8zWGlXGTQTyE/B/+B8+ikFZP7wLizGQSS+hkIwA3hY/d 0BOHTQvtQ+aCJNU5qhZ1rGE9w4aiedSpDry/1up0= X-Virus-Scanned: Debian amavisd-new at filter2.mymailcheap.com Received: from filter2.mymailcheap.com ([127.0.0.1]) by localhost (filter2.mymailcheap.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id sM-Mxk4EuI0s; Mon, 4 Jan 2021 08:28:54 +0100 (CET) Received: from mail20.mymailcheap.com (mail20.mymailcheap.com [51.83.111.147]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by filter2.mymailcheap.com (Postfix) with ESMTPS; Mon, 4 Jan 2021 08:28:54 +0100 (CET) Received: from [148.251.23.173] (ml.mymailcheap.com [148.251.23.173]) by mail20.mymailcheap.com (Postfix) with ESMTP id 2AA9741F21; Mon, 4 Jan 2021 07:28:54 +0000 (UTC) Authentication-Results: mail20.mymailcheap.com; dkim=pass (1024-bit key; unprotected) header.d=aosc.io header.i=@aosc.io header.b="ICXe2nhY"; dkim-atps=neutral AI-Spam-Status: Not processed Received: from ice-e5v2.lan (unknown [59.41.162.25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail20.mymailcheap.com (Postfix) with ESMTPSA id 7C4EA41F21; Mon, 4 Jan 2021 07:28:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=aosc.io; s=default; t=1609745329; bh=ubj56mHRi69L846UzsE9e5xddidrKAo6HI48wtk8xJs=; h=From:To:Cc:Subject:Date:From; b=ICXe2nhYYD7zHjKNPlF3IqYCf/MjCDqhw4rN92ix/6FN0uZTr8Ee/ME4uPj3hOS9z tURv7cqv9pO/oHtDjUmBF4n2fNXu6rWr2ouNaaqABugQyvMPjLYxmYORzAuujwZ6IY WiQJfjMfNSflrWd1f8Oa/BGPbjwu+rbPEUL008/o= From: Icenowy Zheng To: Miklos Szeredi , Amir Goldstein , Xiao Yang Cc: linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Icenowy Zheng , stable@vger.kernel.org Subject: [PATCH v2] ovl: use a dedicated semaphore for dir upperfile caching Date: Mon, 4 Jan 2021 15:28:35 +0800 Message-Id: <20210104072835.147843-1-icenowy@aosc.io> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [4.90 / 20.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(0.00)[aosc.io:s=default]; RECEIVED_SPAMHAUS_PBL(0.00)[59.41.162.25:received]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; R_MISSING_CHARSET(2.50)[]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BROKEN_CONTENT_TYPE(1.50)[]; R_SPF_SOFTFAIL(0.00)[~all:c]; DMARC_NA(0.00)[aosc.io]; ML_SERVERS(-3.10)[148.251.23.173]; DKIM_TRACE(0.00)[aosc.io:+]; RCPT_COUNT_SEVEN(0.00)[7]; MID_CONTAINS_FROM(1.00)[]; FREEMAIL_TO(0.00)[szeredi.hu,gmail.com,cn.fujitsu.com]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:24940, ipnet:148.251.0.0/16, country:DE]; RCVD_COUNT_TWO(0.00)[2]; HFILTER_HELO_BAREIP(3.00)[148.251.23.173,1] X-Rspamd-Queue-Id: 2AA9741F21 X-Rspamd-Server: mail20.mymailcheap.com Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org The function ovl_dir_real_file() currently uses the semaphore of the inode to synchronize write to the upperfile cache field. However, this function will get called by ovl_ioctl_set_flags(), which utilizes the inode semaphore too. In this case ovl_dir_real_file() will try to claim a lock that is owned by a function in its call stack, which won't get released before ovl_dir_real_file() returns. Define a dedicated semaphore for the upperfile cache, so that the deadlock won't happen. Fixes: 61536bed2149 ("ovl: support [S|G]ETFLAGS and FS[S|G]ETXATTR ioctls for directories") Cc: stable@vger.kernel.org # v5.10 Signed-off-by: Icenowy Zheng --- fs/overlayfs/readdir.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 01620ebae1bd..fa1844ff8db4 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -56,6 +56,7 @@ struct ovl_dir_file { struct list_head *cursor; struct file *realfile; struct file *upperfile; + struct semaphore upperfile_sem; }; static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) @@ -874,8 +875,6 @@ struct file *ovl_dir_real_file(const struct file *file, bool want_upper) * Need to check if we started out being a lower dir, but got copied up */ if (!od->is_upper) { - struct inode *inode = file_inode(file); - realfile = READ_ONCE(od->upperfile); if (!realfile) { struct path upperpath; @@ -883,10 +882,10 @@ struct file *ovl_dir_real_file(const struct file *file, bool want_upper) ovl_path_upper(dentry, &upperpath); realfile = ovl_dir_open_realfile(file, &upperpath); - inode_lock(inode); + down(&od->upperfile_sem); if (!od->upperfile) { if (IS_ERR(realfile)) { - inode_unlock(inode); + up(&od->upperfile_sem); return realfile; } smp_store_release(&od->upperfile, realfile); @@ -896,7 +895,7 @@ struct file *ovl_dir_real_file(const struct file *file, bool want_upper) fput(realfile); realfile = od->upperfile; } - inode_unlock(inode); + up(&od->upperfile_sem); } } @@ -959,6 +958,7 @@ static int ovl_dir_open(struct inode *inode, struct file *file) od->realfile = realfile; od->is_real = ovl_dir_is_real(file->f_path.dentry); od->is_upper = OVL_TYPE_UPPER(type); + sema_init(&od->upperfile_sem, 1); file->private_data = od; return 0; -- 2.28.0