The be structure must not be freed when freeing the blkif structure
isn't done. Otherwise a use-after-free of be when unmapping the ring
used for communicating with the frontend will occur in case of a
late call of xenblk_disconnect() (e.g. due to an I/O still active
when trying to disconnect).
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Tested-by: Steven Haigh <netwiz@xxxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
This is a backport of commit 71df1d7ccad1c36f7321d6b3b48f2ea42681c363
for linux-4.4.y branch.
---
drivers/block/xen-blkback/xenbus.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index f53cff42f8da..58f151e283ff 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -266,9 +266,10 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
static void xen_blkif_free(struct xen_blkif *blkif)
{
-
- xen_blkif_disconnect(blkif);
+ WARN_ON(xen_blkif_disconnect(blkif));
xen_vbd_free(&blkif->vbd);
+ kfree(blkif->be->mode);
+ kfree(blkif->be);
/* Make sure everything is drained before shutting down */
BUG_ON(blkif->persistent_gnt_c != 0);
@@ -445,8 +446,6 @@ static int xen_blkbk_remove(struct xenbus_device *dev)
xen_blkif_put(be->blkif);
}
- kfree(be->mode);
- kfree(be);
return 0;
}
--
2.12.3