[PATCH 4.9 050/138] fix a page leak in vhost_scsi_iov_to_sgl() error recovery

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 11d49e9d089ccec81be87c2386dfdd010d7f7f6e upstream.

we are advancing sg as we go, so the pages we need to drop in
case of error are *before* the current sg.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/vhost/scsi.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -693,6 +693,7 @@ vhost_scsi_iov_to_sgl(struct vhost_scsi_
 		      struct scatterlist *sg, int sg_count)
 {
 	size_t off = iter->iov_offset;
+	struct scatterlist *p = sg;
 	int i, ret;
 
 	for (i = 0; i < iter->nr_segs; i++) {
@@ -701,8 +702,8 @@ vhost_scsi_iov_to_sgl(struct vhost_scsi_
 
 		ret = vhost_scsi_map_to_sgl(cmd, base, len, sg, write);
 		if (ret < 0) {
-			for (i = 0; i < sg_count; i++) {
-				struct page *page = sg_page(&sg[i]);
+			while (p < sg) {
+				struct page *page = sg_page(p++);
 				if (page)
 					put_page(page);
 			}