linux-kernel - [PATCH V2 5/7] scsi: storvsc: Fix a bug in copy_from_bounce

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Message-Id: <1427441240-29314-5-git-send-email-kys@microsoft.com>
Date:	Fri, 27 Mar 2015 00:27:18 -0700
From:	"K. Y. Srinivasan" <kys@...rosoft.com>
To:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, ohering@...e.com,
	jbottomley@...allels.com, hch@...radead.org,
	linux-scsi@...r.kernel.org, apw@...onical.com, vkuznets@...hat.com,
	jasowang@...hat.com
Cc:	"K. Y. Srinivasan" <kys@...rosoft.com>, <stable@...r.kernel.org>
Subject: [PATCH V2 5/7] scsi: storvsc: Fix a bug in copy_from_bounce_buffer()

We may exit this function without properly freeing up the maapings
we may have acquired. Fix the bug.

Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Reviewed-by: Long Li <longli@...rosoft.com>
Cc: <stable@...r.kernel.org>
---
 drivers/scsi/storvsc_drv.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index cdf048b..f8e4dd9 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -754,21 +754,22 @@ static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
 			if (bounce_sgl[j].length == PAGE_SIZE) {
 				/* full..move to next entry */
 				sg_kunmap_atomic(bounce_addr);
+				bounce_addr = 0;
 				j++;
+			}
 
-				/* if we need to use another bounce buffer */
-				if (srclen || i != orig_sgl_count - 1)
-					bounce_addr = sg_kmap_atomic(bounce_sgl,j);
+			/* if we need to use another bounce buffer */
+			if (srclen && bounce_addr == 0)
+				bounce_addr = sg_kmap_atomic(bounce_sgl, j);
 
-			} else if (srclen == 0 && i == orig_sgl_count - 1) {
-				/* unmap the last bounce that is < PAGE_SIZE */
-				sg_kunmap_atomic(bounce_addr);
-			}
 		}
 
 		sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
 	}
 
+	if (bounce_addr)
+		sg_kunmap_atomic(bounce_addr);
+
 	local_irq_restore(flags);
 
 	return total_copied;
-- 
1.7.4.1

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