[PATCH 4.4 38/96] fix a page leak in vhost_scsi_iov_to_sgl() error recovery

[Greg Kroah-Hartman]

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

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

From: Al Viro <v...@zeniv.linux.org.uk>

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 <v...@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

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

--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -703,6 +703,7 @@ 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++) {
@@ -711,8 +712,8 @@ 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);
                        }