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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0276BC32771 for ; Fri, 19 Aug 2022 15:49:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350151AbiHSPtj (ORCPT ); Fri, 19 Aug 2022 11:49:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50742 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350256AbiHSPsq (ORCPT ); Fri, 19 Aug 2022 11:48:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E6F865676; Fri, 19 Aug 2022 08:47:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 43A1B61639; Fri, 19 Aug 2022 15:47:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D7B9C433C1; Fri, 19 Aug 2022 15:47:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660924050; bh=zE8eCFpUAdOKqXM9UxvCfhapw2jHaqJ6PSiltR6ceXw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zrPtT0ju9Rp6Pwb/tXz2gybKcAgM439FiWQhGhOXT/HnB5azbk9ynQyOgt2tRNuMa F1QexPnGx5czWGoUcL0V1eZyoza7PuzBOYWMGahtw8ydpc7pRYL/fJpl8xynC+b/xu r+hvekZzMZBu9C6/KShT1Wn/Hu3KzV5t5hIhO7U8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hongbo Yin , Jiachen Zhang , Tianci Zhang , Miklos Szeredi Subject: [PATCH 5.10 038/545] ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh() Date: Fri, 19 Aug 2022 17:36:48 +0200 Message-Id: <20220819153830.937824384@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819153829.135562864@linuxfoundation.org> References: <20220819153829.135562864@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiachen Zhang commit dd524b7f317de8d31d638cbfdc7be4cf9b770e42 upstream. Some code paths cannot guarantee the inode have any dentry alias. So WARN_ON() all !dentry may flood the kernel logs. For example, when an overlayfs inode is watched by inotifywait (1), and someone is trying to read the /proc/$(pidof inotifywait)/fdinfo/INOTIFY_FD, at that time if the dentry has been reclaimed by kernel (such as echo 2 > /proc/sys/vm/drop_caches), there will be a WARN_ON(). The printed call stack would be like: ? show_mark_fhandle+0xf0/0xf0 show_mark_fhandle+0x4a/0xf0 ? show_mark_fhandle+0xf0/0xf0 ? seq_vprintf+0x30/0x50 ? seq_printf+0x53/0x70 ? show_mark_fhandle+0xf0/0xf0 inotify_fdinfo+0x70/0x90 show_fdinfo.isra.4+0x53/0x70 seq_show+0x130/0x170 seq_read+0x153/0x440 vfs_read+0x94/0x150 ksys_read+0x5f/0xe0 do_syscall_64+0x59/0x1e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 So let's drop WARN_ON() to avoid kernel log flooding. Reported-by: Hongbo Yin Signed-off-by: Jiachen Zhang Signed-off-by: Tianci Zhang Fixes: 8ed5eec9d6c4 ("ovl: encode pure upper file handles") Cc: # v4.16 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/export.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -257,7 +257,7 @@ static int ovl_encode_fh(struct inode *i return FILEID_INVALID; dentry = d_find_any_alias(inode); - if (WARN_ON(!dentry)) + if (!dentry) return FILEID_INVALID; bytes = ovl_dentry_to_fid(dentry, fid, buflen);