From patchwork Wed Nov 8 04:31:50 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nicholas A. Bellinger" X-Patchwork-Id: 10047655 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CDD12603FA for ; Wed, 8 Nov 2017 04:21:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BF82B2A3D5 for ; Wed, 8 Nov 2017 04:21:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B4749294AD; Wed, 8 Nov 2017 04:21:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1D8C6294AD for ; Wed, 8 Nov 2017 04:21:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968AbdKHEVn (ORCPT ); Tue, 7 Nov 2017 23:21:43 -0500 Received: from mail.linux-iscsi.org ([67.23.28.174]:54052 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751931AbdKHEVk (ORCPT ); Tue, 7 Nov 2017 23:21:40 -0500 Received: from linux-iscsi.org (localhost [127.0.0.1]) by linux-iscsi.org (Postfix) with ESMTP id 632824000A; Wed, 8 Nov 2017 04:32:01 +0000 (UTC) From: "Nicholas A. Bellinger" To: target-devel Cc: linux-scsi , lkml , Nicholas Bellinger , Donald White , Mike Christie , Hannes Reinecke Subject: [PATCH 4/6] target: Avoid early CMD_T_PRE_EXECUTE failures during ABORT_TASK Date: Wed, 8 Nov 2017 04:31:50 +0000 Message-Id: <1510115512-15617-5-git-send-email-nab@linux-iscsi.org> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1510115512-15617-1-git-send-email-nab@linux-iscsi.org> References: <1510115512-15617-1-git-send-email-nab@linux-iscsi.org> Sender: target-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Nicholas Bellinger This patch fixes bug where early se_cmd exceptions that occur before backend execution can result in use-after-free if/when a subsequent ABORT_TASK occurs for the same tag. Since an early se_cmd exception will have had se_cmd added to se_session->sess_cmd_list via target_get_sess_cmd(), it will not have CMD_T_COMPLETE set by the usual target_complete_cmd() backend completion path. This causes a subsequent ABORT_TASK + __target_check_io_state() to signal ABORT_TASK should proceed. As core_tmr_abort_task() executes, it will bring the outstanding se_cmd->cmd_kref count down to zero releasing se_cmd, after se_cmd has already been queued with error status into fabric driver response path code. To address this bug, introduce a CMD_T_PRE_EXECUTE bit that is set at target_get_sess_cmd() time, and cleared immediately before backend driver dispatch in target_execute_cmd() once CMD_T_ACTIVE is set. Then, check CMD_T_PRE_EXECUTE within __target_check_io_state() to determine when an early exception has occured, and avoid aborting this se_cmd since it will have already been queued into fabric driver response path code. Reported-by: Donald White Cc: Donald White Cc: Mike Christie Cc: Hannes Reinecke Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_tmr.c | 9 +++++++++ drivers/target/target_core_transport.c | 2 ++ include/target/target_core_base.h | 1 + 3 files changed, 12 insertions(+) diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index 61909b2..9c7bc1c 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -133,6 +133,15 @@ static bool __target_check_io_state(struct se_cmd *se_cmd, spin_unlock(&se_cmd->t_state_lock); return false; } + if (se_cmd->transport_state & CMD_T_PRE_EXECUTE) { + if (se_cmd->scsi_status) { + pr_debug("Attempted to abort io tag: %llu early failure" + " status: 0x%02x\n", se_cmd->tag, + se_cmd->scsi_status); + spin_unlock(&se_cmd->t_state_lock); + return false; + } + } if (sess->sess_tearing_down || se_cmd->cmd_wait_set) { pr_debug("Attempted to abort io tag: %llu already shutdown," " skipping\n", se_cmd->tag); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 0e89db8..58caacd 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1975,6 +1975,7 @@ void target_execute_cmd(struct se_cmd *cmd) } cmd->t_state = TRANSPORT_PROCESSING; + cmd->transport_state &= ~CMD_T_PRE_EXECUTE; cmd->transport_state |= CMD_T_ACTIVE | CMD_T_SENT; spin_unlock_irq(&cmd->t_state_lock); @@ -2667,6 +2668,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) ret = -ESHUTDOWN; goto out; } + se_cmd->transport_state |= CMD_T_PRE_EXECUTE; list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list); out: spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index d3139a9..ccf501b 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -490,6 +490,7 @@ struct se_cmd { #define CMD_T_STOP (1 << 5) #define CMD_T_TAS (1 << 10) #define CMD_T_FABRIC_STOP (1 << 11) +#define CMD_T_PRE_EXECUTE (1 << 12) spinlock_t t_state_lock; struct kref cmd_kref; struct completion t_transport_stop_comp;