From patchwork Mon Dec 28 12:50:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 355006 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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED, 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 A01D8C4332E for ; Mon, 28 Dec 2020 13:56:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E69C207B2 for ; Mon, 28 Dec 2020 13:56:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405372AbgL1Nzz (ORCPT ); Mon, 28 Dec 2020 08:55:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:56998 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405370AbgL1Nzz (ORCPT ); Mon, 28 Dec 2020 08:55:55 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 02DDB20715; Mon, 28 Dec 2020 13:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609163739; bh=y0oZAVE1vDTEKKHqWovCEf+eHw3ANfkoHxUvLOkcbZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Jzb5TV4BOksD07KArUvbASKOkQ/5yN5YW0d4nb8XALhBCUjz5EnTyifAmetcfThEk cXG0epgpP0IjjRBthWPun1cvgZ862yotj6NO0pvwLkkhIT+x4w8ZeUSkKTwHBLd0re W5OhHD+PJk/Q1H02Grl4aXK0mQ6Tjf0TRNsAbm5g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jeff Layton , Luis Henriques , Ilya Dryomov Subject: [PATCH 5.4 391/453] ceph: fix race in concurrent __ceph_remove_cap invocations Date: Mon, 28 Dec 2020 13:50:27 +0100 Message-Id: <20201228124956.025727870@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124937.240114599@linuxfoundation.org> References: <20201228124937.240114599@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Luis Henriques commit e5cafce3ad0f8652d6849314d951459c2bff7233 upstream. A NULL pointer dereference may occur in __ceph_remove_cap with some of the callbacks used in ceph_iterate_session_caps, namely trim_caps_cb and remove_session_caps_cb. Those callers hold the session->s_mutex, so they are prevented from concurrent execution, but ceph_evict_inode does not. Since the callers of this function hold the i_ceph_lock, the fix is simply a matter of returning immediately if caps->ci is NULL. Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/43272 Suggested-by: Jeff Layton Signed-off-by: Luis Henriques Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman --- fs/ceph/caps.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1052,12 +1052,19 @@ void __ceph_remove_cap(struct ceph_cap * { struct ceph_mds_session *session = cap->session; struct ceph_inode_info *ci = cap->ci; - struct ceph_mds_client *mdsc = - ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc; + struct ceph_mds_client *mdsc; int removed = 0; + /* 'ci' being NULL means the remove have already occurred */ + if (!ci) { + dout("%s: cap inode is NULL\n", __func__); + return; + } + dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode); + mdsc = ceph_inode_to_client(&ci->vfs_inode)->mdsc; + /* remove from inode's cap rbtree, and clear auth cap */ rb_erase(&cap->ci_node, &ci->i_caps); if (ci->i_auth_cap == cap)