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=-10.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 7A494C04EB9 for ; Wed, 5 Dec 2018 09:41:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A5342084C for ; Wed, 5 Dec 2018 09:41:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="rn+HcoPh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A5342084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728843AbeLEJlG (ORCPT ); Wed, 5 Dec 2018 04:41:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:45482 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727514AbeLEJlC (ORCPT ); Wed, 5 Dec 2018 04:41:02 -0500 Received: from sasha-vm.mshome.net (unknown [213.57.143.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 199B120850; Wed, 5 Dec 2018 09:41:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544002862; bh=xSsXuhGdBxSpS2iw2aQoeric6mX2S0zyQGx+7LHxbuo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rn+HcoPh7IUf4RmFRWoRPdpLt7TKydhYV/hCTuT84vgzXyROKAOcvrqTmgP/0t19d MlWjBKf/73XG+UgNTRumow+10aW/rgZ1WlDemYvMQzTIOS+G8mSpxHafR6gCW9ORZ8 gSHpBl2VT0SRQkHvglX/3z7xBF5ue2HMLf1lHFUQ= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: David Howells , Sasha Levin Subject: [PATCH AUTOSEL 4.19 091/123] cachefiles: Fix an assertion failure when trying to update a failed object Date: Wed, 5 Dec 2018 04:35:23 -0500 Message-Id: <20181205093555.5386-91-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181205093555.5386-1-sashal@kernel.org> References: <20181205093555.5386-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells [ Upstream commit e6bc06faf64a83384cc0abc537df954c9d3ff942 ] If cachefiles gets an error other then ENOENT when trying to look up an object in the cache (in this case, EACCES), the object state machine will eventually transition to the DROP_OBJECT state. This state invokes fscache_drop_object() which tries to sync the auxiliary data with the cache (this is done lazily since commit 402cb8dda949d) on an incomplete cache object struct. The problem comes when cachefiles_update_object_xattr() is called to rewrite the xattr holding the data. There's an assertion there that the cache object points to a dentry as we're going to update its xattr. The assertion trips, however, as dentry didn't get set. Fix the problem by skipping the update in cachefiles if the object doesn't refer to a dentry. A better way to do it could be to skip the update from the DROP_OBJECT state handler in fscache, but that might deny the cache the opportunity to update intermediate state. If this error occurs, the kernel log includes lines that look like the following: CacheFiles: Lookup failed error -13 CacheFiles: CacheFiles: Assertion failed ------------[ cut here ]------------ kernel BUG at fs/cachefiles/xattr.c:138! ... Workqueue: fscache_object fscache_object_work_func [fscache] RIP: 0010:cachefiles_update_object_xattr.cold.4+0x18/0x1a [cachefiles] ... Call Trace: cachefiles_update_object+0xdd/0x1c0 [cachefiles] fscache_update_aux_data+0x23/0x30 [fscache] fscache_drop_object+0x18e/0x1c0 [fscache] fscache_object_work_func+0x74/0x2b0 [fscache] process_one_work+0x18d/0x340 worker_thread+0x2e/0x390 ? pwq_unbound_release_workfn+0xd0/0xd0 kthread+0x112/0x130 ? kthread_bind+0x30/0x30 ret_from_fork+0x35/0x40 Note that there are actually two issues here: (1) EACCES happened on a cache object and (2) an oops occurred. I think that the second is a consequence of the first (it certainly looks like it ought to be). This patch only deals with the second. Fixes: 402cb8dda949 ("fscache: Attach the index key and aux data to the cookie") Reported-by: Zhibin Li Signed-off-by: David Howells Signed-off-by: Sasha Levin --- fs/cachefiles/xattr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c index 0a29a00aed2e..511e6c68156a 100644 --- a/fs/cachefiles/xattr.c +++ b/fs/cachefiles/xattr.c @@ -135,7 +135,8 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object, struct dentry *dentry = object->dentry; int ret; - ASSERT(dentry); + if (!dentry) + return -ESTALE; _enter("%p,#%d", object, auxdata->len); -- 2.17.1