[PATCH AUTOSEL for 4.9 50/52] xen/gntdev: Fix partial gntdev_mmap() cleanup

Sasha Levin
2018-02-03T18:06:43Z

From: Ross Lagerwall <ross.lagerwall@citrix.com>

[ Upstream commit cf2acf66ad43abb39735568f55e1f85f9844e990 ]

When cleaning up after a partially successful gntdev_mmap(), unmap the
successfully mapped grant pages otherwise Xen will kill the domain if
in debug mode (Attempt to implicitly unmap a granted PTE) or Linux will
kill the process and emit "BUG: Bad page map in process" if Xen is in
release mode.

This is only needed when use_ptemod is true because gntdev_put_map()
will unmap grant pages itself when use_ptemod is false.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/xen/gntdev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 54c4c4183fbe..910b5d40c6e9 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1077,8 +1077,10 @@ unlock_out:
out_unlock_put:
mutex_unlock(&priv->lock);
out_put_map:
- if (use_ptemod)
+ if (use_ptemod) {
map->vma = NULL;
+ unmap_grant_pages(map, 0, map->count);
+ }
gntdev_put_map(priv, map);
return err;
}
--
2.11.0