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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 DF245C169C4 for ; Tue, 29 Jan 2019 11:52:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF8BC2086C for ; Tue, 29 Jan 2019 11:52:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548762764; bh=nwT3rq+crU4ZFJMx/8Qr7ZZIRt27XwLYX/wl/wsWqkw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Mx8S2cwX322OvHUrJ1RDV8VJORNVK90wcQ/P5sS4QHSLJbzCPcXJavgvqZpDoNM9U LrAWxRrsobwODoQ420naRt+nyt7fITXA7lY/WPS/D48Mfn+ndO5BqaR4tXYtcW8QST M6NI+9IuOAmVZ6QuNXb0BPIJ3VPJx2nEnyx5knVY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732160AbfA2Lwn (ORCPT ); Tue, 29 Jan 2019 06:52:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:44550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731038AbfA2Lwl (ORCPT ); Tue, 29 Jan 2019 06:52:41 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 0745E2083B; Tue, 29 Jan 2019 11:52:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548762760; bh=nwT3rq+crU4ZFJMx/8Qr7ZZIRt27XwLYX/wl/wsWqkw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mhrGDO4QuRovvF/hw9st1I013xV+LwBE0CDr6q8EawhjNAAy5H4aCaTUQHPiLgkIf CMpdouI6Ohi712dMM8jgZVrOjH81QIsfgnZgGddFf5M4bgb8O4E/YRHPdhG6usuODI X+anq4iVdAfRs7TxJXoKyNHFn3Jrw9k/V8wkWBB0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Shilovsky , Ronnie Sahlberg , Steve French Subject: [PATCH 4.9 23/44] CIFS: Do not reconnect TCP session in add_credits() Date: Tue, 29 Jan 2019 12:36:18 +0100 Message-Id: <20190129113141.826517383@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190129113139.826927690@linuxfoundation.org> References: <20190129113139.826927690@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavel Shilovsky commit ef68e831840c40c7d01b328b3c0f5d8c4796c232 upstream. When executing add_credits() we currently call cifs_reconnect() if the number of credits is zero and there are no requests in flight. In this case we may call cifs_reconnect() recursively twice and cause memory corruption given the following sequence of functions: mid1.callback() -> add_credits() -> cifs_reconnect() -> -> mid2.callback() -> add_credits() -> cifs_reconnect(). Fix this by avoiding to call cifs_reconnect() in add_credits() and checking for zero credits in the demultiplex thread. Cc: Signed-off-by: Pavel Shilovsky Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/connect.c | 21 +++++++++++++++++++++ fs/cifs/smb2ops.c | 32 +++++++++++++++++++++++++------- 2 files changed, 46 insertions(+), 7 deletions(-) --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -518,6 +518,21 @@ server_unresponsive(struct TCP_Server_In return false; } +static inline bool +zero_credits(struct TCP_Server_Info *server) +{ + int val; + + spin_lock(&server->req_lock); + val = server->credits + server->echo_credits + server->oplock_credits; + if (server->in_flight == 0 && val == 0) { + spin_unlock(&server->req_lock); + return true; + } + spin_unlock(&server->req_lock); + return false; +} + static int cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg) { @@ -530,6 +545,12 @@ cifs_readv_from_socket(struct TCP_Server for (total_read = 0; msg_data_left(smb_msg); total_read += length) { try_to_freeze(); + /* reconnect if no credits and no requests in flight */ + if (zero_credits(server)) { + cifs_reconnect(server); + return -ECONNABORTED; + } + if (server_unresponsive(server)) return -ECONNABORTED; --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -30,6 +30,7 @@ #include "smb2glob.h" #include "cifs_ioctl.h" +/* Change credits for different ops and return the total number of credits */ static int change_conf(struct TCP_Server_Info *server) { @@ -37,17 +38,15 @@ change_conf(struct TCP_Server_Info *serv server->oplock_credits = server->echo_credits = 0; switch (server->credits) { case 0: - return -1; + return 0; case 1: server->echoes = false; server->oplocks = false; - cifs_dbg(VFS, "disabling echoes and oplocks\n"); break; case 2: server->echoes = true; server->oplocks = false; server->echo_credits = 1; - cifs_dbg(FYI, "disabling oplocks\n"); break; default: server->echoes = true; @@ -60,14 +59,15 @@ change_conf(struct TCP_Server_Info *serv server->echo_credits = 1; } server->credits -= server->echo_credits + server->oplock_credits; - return 0; + return server->credits + server->echo_credits + server->oplock_credits; } static void smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add, const int optype) { - int *val, rc = 0; + int *val, rc = -1; + spin_lock(&server->req_lock); val = server->ops->get_credits_field(server, optype); *val += add; @@ -91,8 +91,26 @@ smb2_add_credits(struct TCP_Server_Info } spin_unlock(&server->req_lock); wake_up(&server->request_q); - if (rc) - cifs_reconnect(server); + + if (server->tcpStatus == CifsNeedReconnect) + return; + + switch (rc) { + case -1: + /* change_conf hasn't been executed */ + break; + case 0: + cifs_dbg(VFS, "Possible client or server bug - zero credits\n"); + break; + case 1: + cifs_dbg(VFS, "disabling echoes and oplocks\n"); + break; + case 2: + cifs_dbg(FYI, "disabling oplocks\n"); + break; + default: + cifs_dbg(FYI, "add %u credits total=%d\n", add, rc); + } } static void