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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 26CF9C7618F for ; Wed, 24 Jul 2019 20:27:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF874204EC for ; Wed, 24 Jul 2019 20:27:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564000029; bh=OR9DaQIEQw3qnxF0j8VZbZv+NIuXumN8R7MCJwQNeYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=wVthjIxHFxKBfpvgdBc3sEfTzj4palXDqALOC+sEUWqZSLq1gwXzpdOQmvruJjFS3 IACA96AnIaEnI9BHdU0d01FBAlc2kvBvJuxGvOAu6HNrsgLIjyrhYZdETkBafLV47o 7ft2AyhGUU+nbdMPgj4Vi/GYZ0TnMuKAl4aRQ7VU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389086AbfGXTgN (ORCPT ); Wed, 24 Jul 2019 15:36:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:35836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389289AbfGXTgN (ORCPT ); Wed, 24 Jul 2019 15:36:13 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3C50A229F3; Wed, 24 Jul 2019 19:36:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563996971; bh=OR9DaQIEQw3qnxF0j8VZbZv+NIuXumN8R7MCJwQNeYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sOA6/cgTVIS1yciJgCOt/qBTs+TpsIo2R3Vv/eim8PnmJ/VWqPqJzURXOFSZgT3Eb pB79rosTu7HsoaWeXz91bOkmfM58U8m0iFmPx4PjgECDwK2M2ZyDwqePrU4K6Tuf7t rrYGNKBh0YBOKedAUDvVgDOtLASNnVS/sSU/01rk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aurelien Aptel , Pavel Shilovsky , Steve French Subject: [PATCH 5.2 279/413] CIFS: fix deadlock in cached root handling Date: Wed, 24 Jul 2019 21:19:30 +0200 Message-Id: <20190724191756.262519456@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190724191735.096702571@linuxfoundation.org> References: <20190724191735.096702571@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Aurelien Aptel commit 7e5a70ad88b1e6f6d9b934b2efb41afff496820f upstream. Prevent deadlock between open_shroot() and cifs_mark_open_files_invalid() by releasing the lock before entering SMB2_open, taking it again after and checking if we still need to use the result. Link: https://lore.kernel.org/linux-cifs/684ed01c-cbca-2716-bc28-b0a59a0f8521@prodrive-technologies.com/T/#u Fixes: 3d4ef9a15343 ("smb3: fix redundant opens on root") Signed-off-by: Aurelien Aptel Reviewed-by: Pavel Shilovsky Signed-off-by: Steve French CC: Stable Signed-off-by: Greg Kroah-Hartman --- fs/cifs/smb2ops.c | 46 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 45 insertions(+), 1 deletion(-) --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -694,8 +694,51 @@ int open_shroot(unsigned int xid, struct smb2_set_related(&rqst[1]); + /* + * We do not hold the lock for the open because in case + * SMB2_open needs to reconnect, it will end up calling + * cifs_mark_open_files_invalid() which takes the lock again + * thus causing a deadlock + */ + + mutex_unlock(&tcon->crfid.fid_mutex); rc = compound_send_recv(xid, ses, flags, 2, rqst, resp_buftype, rsp_iov); + mutex_lock(&tcon->crfid.fid_mutex); + + /* + * Now we need to check again as the cached root might have + * been successfully re-opened from a concurrent process + */ + + if (tcon->crfid.is_valid) { + /* work was already done */ + + /* stash fids for close() later */ + struct cifs_fid fid = { + .persistent_fid = pfid->persistent_fid, + .volatile_fid = pfid->volatile_fid, + }; + + /* + * caller expects this func to set pfid to a valid + * cached root, so we copy the existing one and get a + * reference. + */ + memcpy(pfid, tcon->crfid.fid, sizeof(*pfid)); + kref_get(&tcon->crfid.refcount); + + mutex_unlock(&tcon->crfid.fid_mutex); + + if (rc == 0) { + /* close extra handle outside of crit sec */ + SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid); + } + goto oshr_free; + } + + /* Cached root is still invalid, continue normaly */ + if (rc) goto oshr_exit; @@ -729,8 +772,9 @@ int open_shroot(unsigned int xid, struct (char *)&tcon->crfid.file_all_info)) tcon->crfid.file_all_info_is_valid = 1; - oshr_exit: +oshr_exit: mutex_unlock(&tcon->crfid.fid_mutex); +oshr_free: SMB2_open_free(&rqst[0]); SMB2_query_info_free(&rqst[1]); free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);