Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964985AbdLRQQm (ORCPT ); Mon, 18 Dec 2017 11:16:42 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:44786 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936367AbdLRQQa (ORCPT ); Mon, 18 Dec 2017 11:16:30 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaofei Tan , John Garry , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 4.14 131/178] scsi: hisi_sas: fix the risk of freeing slot twice Date: Mon, 18 Dec 2017 16:49:27 +0100 Message-Id: <20171218152926.286304896@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171218152920.567991776@linuxfoundation.org> References: <20171218152920.567991776@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2228 Lines: 69 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiaofei Tan [ Upstream commit 6ba0fbc35aa9f3bc8c12be3b4047055c9ce2ac92 ] The function hisi_sas_slot_task_free() is used to free the slot and do tidy-up of LLDD resources. The LLDD generally should know the state of a slot and decide when to free it, and it should only be done once. For some scenarios, we really don't know the state, like when TMF timeout. In this case, we check task->lldd_task before calling hisi_sas_slot_task_free(). However, we may miss some scenarios when we should also check task->lldd_task, and it is not SMP safe to check task->lldd_task as we don't protect it within spin lock. This patch is to fix this risk of freeing slot twice, as follows: 1. Check task->lldd_task in the hisi_sas_slot_task_free(), and give up freeing of this time if task->lldd_task is NULL. 2. Set slot->buf to NULL after it is freed. Signed-off-by: Xiaofei Tan Signed-off-by: John Garry Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/hisi_sas/hisi_sas_main.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/scsi/hisi_sas/hisi_sas_main.c +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c @@ -185,13 +185,16 @@ void hisi_sas_slot_task_free(struct hisi struct domain_device *device = task->dev; struct hisi_sas_device *sas_dev = device->lldd_dev; + if (!task->lldd_task) + return; + + task->lldd_task = NULL; + if (!sas_protocol_ata(task->task_proto)) if (slot->n_elem) dma_unmap_sg(dev, task->scatter, slot->n_elem, task->data_dir); - task->lldd_task = NULL; - if (sas_dev) atomic64_dec(&sas_dev->running_req); } @@ -199,8 +202,8 @@ void hisi_sas_slot_task_free(struct hisi if (slot->buf) dma_pool_free(hisi_hba->buffer_pool, slot->buf, slot->buf_dma); - list_del_init(&slot->entry); + slot->buf = NULL; slot->task = NULL; slot->port = NULL; hisi_sas_slot_index_free(hisi_hba, slot->idx);