From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from youngberry.canonical.com ([91.189.89.112]:49092 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754798AbbH0WNY (ORCPT ); Thu, 27 Aug 2015 18:13:24 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Brian King , James Bottomley , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 107/130] ipr: Fix incorrect trace indexing Date: Thu, 27 Aug 2015 15:11:38 -0700 Message-Id: <1440713521-5906-108-git-send-email-kamal@canonical.com> In-Reply-To: <1440713521-5906-1-git-send-email-kamal@canonical.com> References: <1440713521-5906-1-git-send-email-kamal@canonical.com> Sender: stable-owner@vger.kernel.org List-ID: 3.19.8-ckt6 -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: Kamal Mostafa --- 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 921e294..05d5350 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 70b0647..6948f9f 100644 --- a/drivers/scsi/ipr.h +++ b/drivers/scsi/ipr.h @@ -1479,6 +1479,7 @@ 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" -- 1.9.1