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 5585FCCA48E for ; Tue, 7 Jun 2022 21:54:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382593AbiFGVvg (ORCPT ); Tue, 7 Jun 2022 17:51:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378316AbiFGU4G (ORCPT ); Tue, 7 Jun 2022 16:56:06 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 254E62010C7; Tue, 7 Jun 2022 11:44:16 -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 D92096157F; Tue, 7 Jun 2022 18:44:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C25AC385A2; Tue, 7 Jun 2022 18:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654627455; bh=2b3EwAxT/IxY3yiIFVjw+wSEWXH1+Ouo/kRi/T0Wbxw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o8BOvujUb628fV2yrIc+s0O5aZxa4CYC2MF6HD8ihVTP1ZaDSvmCYG1MFZ6KoeDLQ DrCsfXNRP3gzwNKfRFkdBoAyZuJkFPWTJbcnEbOtVZC/If2gDrvD73pER1Prwgjw9a zGyUyt9/Tk/N6mVnBWtr1NU7l/91EY/piuvBYMgA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ondrej Hubsch , Ronnie Sahlberg , "Paulo Alcantara (SUSE)" , Steve French Subject: [PATCH 5.17 747/772] SMB3: EBADF/EIO errors in rename/open caused by race condition in smb2_compound_op Date: Tue, 7 Jun 2022 19:05:39 +0200 Message-Id: <20220607165011.041254831@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164948.980838585@linuxfoundation.org> References: <20220607164948.980838585@linuxfoundation.org> User-Agent: quilt/0.66 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: Steve French commit 0a55cf74ffb5d004b93647e4389096880ce37d6b upstream. There is a race condition in smb2_compound_op: after_close: num_rqst++; if (cfile) { cifsFileInfo_put(cfile); // sends SMB2_CLOSE to the server cfile = NULL; This is triggered by smb2_query_path_info operation that happens during revalidate_dentry. In smb2_query_path_info, get_readable_path is called to load the cfile, increasing the reference counter. If in the meantime, this reference becomes the very last, this call to cifsFileInfo_put(cfile) will trigger a SMB2_CLOSE request sent to the server just before sending this compound request – and so then the compound request fails either with EBADF/EIO depending on the timing at the server, because the handle is already closed. In the first scenario, the race seems to be happening between smb2_query_path_info triggered by the rename operation, and between “cleanup” of asynchronous writes – while fsync(fd) likely waits for the asynchronous writes to complete, releasing the writeback structures can happen after the close(fd) call. So the EBADF/EIO errors will pop up if the timing is such that: 1) There are still outstanding references after close(fd) in the writeback structures 2) smb2_query_path_info successfully fetches the cfile, increasing the refcounter by 1 3) All writeback structures release the same cfile, reducing refcounter to 1 4) smb2_compound_op is called with that cfile In the second scenario, the race seems to be similar – here open triggers the smb2_query_path_info operation, and if all other threads in the meantime decrease the refcounter to 1 similarly to the first scenario, again SMB2_CLOSE will be sent to the server just before issuing the compound request. This case is harder to reproduce. See https://bugzilla.samba.org/show_bug.cgi?id=15051 Cc: stable@vger.kernel.org Fixes: 8de9e86c67ba ("cifs: create a helper to find a writeable handle by path name") Signed-off-by: Ondrej Hubsch Reviewed-by: Ronnie Sahlberg Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/smb2inode.c | 2 -- 1 file changed, 2 deletions(-) --- a/fs/cifs/smb2inode.c +++ b/fs/cifs/smb2inode.c @@ -362,8 +362,6 @@ smb2_compound_op(const unsigned int xid, num_rqst++; if (cfile) { - cifsFileInfo_put(cfile); - cfile = NULL; rc = compound_send_recv(xid, ses, server, flags, num_rqst - 2, &rqst[1], &resp_buftype[1],