[PATCH AUTOSEL 4.9 4/7] xen/blkback: fix memory leaks

[Sasha Levin]

From: Wenwen Wang <wenwen@xxxxxxxxxx>

[ Upstream commit ae78ca3cf3d9e9f914bfcd0bc5c389ff18b9c2e0 ]

In read_per_ring_refs(), after 'req' and related memory regions are
allocated, xen_blkif_map() is invoked to map the shared frame, irq, and
etc. However, if this mapping process fails, no cleanup is performed,
leading to memory leaks. To fix this issue, invoke the cleanup before
returning the error.

Acked-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Wenwen Wang <wenwen@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/block/xen-blkback/xenbus.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 5dfe6e8af1408..ad736d7de8383 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -967,6 +967,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
 	}
 	blkif->nr_ring_pages = nr_grefs;
 
+	err = -ENOMEM;
 	for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
 		req = kzalloc(sizeof(*req), GFP_KERNEL);
 		if (!req)
@@ -989,7 +990,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
 	err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
 	if (err) {
 		xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
-		return err;
+		goto fail;
 	}
 
 	return 0;
@@ -1009,8 +1010,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
 		}
 		kfree(req);
 	}
-	return -ENOMEM;
-
+	return err;
 }
 
 static int connect_ring(struct backend_info *be)
-- 
2.20.1