Patch "ipr: Fix incorrect trace indexing" has been added to the 3.10-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ipr: Fix incorrect trace indexing

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ipr-fix-incorrect-trace-indexing.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From bb7c54339e6a10ecce5c4961adf5e75b3cf0af30 Mon Sep 17 00:00:00 2001
From: Brian King <brking@linux.vnet.ibm.com>
Date: Tue, 14 Jul 2015 11:41:31 -0500
Subject: ipr: Fix incorrect trace indexing

From: Brian King <brking@linux.vnet.ibm.com>

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 <wenxiong@linux.vnet.ibm.com>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/ipr.c |    5 +++--
 drivers/scsi/ipr.h |    1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -554,9 +554,10 @@ static void ipr_trc_hook(struct ipr_cmnd
 {
 	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;
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -1452,6 +1452,7 @@ 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"


Patches currently in stable-queue which might be from brking@linux.vnet.ibm.com are

queue-3.10/ipr-fix-invalid-array-indexing-for-hrrq.patch
queue-3.10/ipr-fix-incorrect-trace-indexing.patch
queue-3.10/ipr-fix-locking-for-unit-attention-handling.patch