From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759456AbbIDNJO (ORCPT ); Fri, 4 Sep 2015 09:09:14 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49853 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759389AbbIDNJE (ORCPT ); Fri, 4 Sep 2015 09:09:04 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Brian King , James Bottomley , Luis Henriques Subject: [PATCH 3.16.y-ckt 021/130] ipr: Fix incorrect trace indexing Date: Fri, 4 Sep 2015 14:06:49 +0100 Message-Id: <1441372118-5933-22-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1441372118-5933-1-git-send-email-luis.henriques@canonical.com> References: <1441372118-5933-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Brian King commit bb7c54339e6a10ecce5c4961adf5e75b3cf0af30 upstream. When ipr's internal driver trace was changed to an atomic, a signed/unsigned bug slipped in which results in us indexing backwards in our memory buffer writing on memory that does not belong to us. This patch fixes this by removing the modulo and instead just mask off the low bits. Tested-by: Wen Xiong Reviewed-by: Wen Xiong Reviewed-by: Gabriel Krisman Bertazi Signed-off-by: Brian King Reviewed-by: Martin K. Petersen Signed-off-by: James Bottomley Signed-off-by: Luis Henriques --- drivers/scsi/ipr.c | 5 +++-- drivers/scsi/ipr.h | 1 + 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c index debc569ab26c..2f49d7b01485 100644 --- a/drivers/scsi/ipr.c +++ b/drivers/scsi/ipr.c @@ -592,9 +592,10 @@ static void ipr_trc_hook(struct ipr_cmnd *ipr_cmd, { struct ipr_trace_entry *trace_entry; struct ipr_ioa_cfg *ioa_cfg = ipr_cmd->ioa_cfg; + unsigned int trace_index; - trace_entry = &ioa_cfg->trace[atomic_add_return - (1, &ioa_cfg->trace_index)%IPR_NUM_TRACE_ENTRIES]; + trace_index = atomic_add_return(1, &ioa_cfg->trace_index) & IPR_TRACE_INDEX_MASK; + trace_entry = &ioa_cfg->trace[trace_index]; trace_entry->time = jiffies; trace_entry->op_code = ipr_cmd->ioarcb.cmd_pkt.cdb[0]; trace_entry->type = type; diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h index b22b23586f93..2459391105fc 100644 --- a/drivers/scsi/ipr.h +++ b/drivers/scsi/ipr.h @@ -1480,6 +1480,7 @@ struct ipr_ioa_cfg { #define IPR_NUM_TRACE_INDEX_BITS 8 #define IPR_NUM_TRACE_ENTRIES (1 << IPR_NUM_TRACE_INDEX_BITS) +#define IPR_TRACE_INDEX_MASK (IPR_NUM_TRACE_ENTRIES - 1) #define IPR_TRACE_SIZE (sizeof(struct ipr_trace_entry) * IPR_NUM_TRACE_ENTRIES) char trace_start[8]; #define IPR_TRACE_START_LABEL "trace"