Xen/gntdev: correct error checking in gntdev_map_grant_pages()

commit ebee0eab08594b2bd5db716288a4f1ae5936e9bc upstream.

Failure of the kernel part of the mapping operation should also be
indicated as an error to the caller, or else it may assume the
respective kernel VA is okay to access.

Furthermore gnttab_map_refs() failing still requires recording
successfully mapped handles, so they can be unmapped subsequently. This
in turn requires there to be a way to tell full hypercall failure from
partial success - preset map_op status fields such that they won't
"happen" to look as if the operation succeeded.

Also again use GNTST_okay instead of implying its value (zero).

This is part of XSA-361.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 0f522cd916642870f2815596afa3f37e28e66bde..e953ea34b3e43190047a91028fe2ca893ff49197 100644 (file)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -344,21 +344,22 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
        pr_debug("map %d+%d\n", map->index, map->count);
        err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
                        map->pages, map->count);
-       if (err)
-               return err;
 
        for (i = 0; i < map->count; i++) {
-               if (map->map_ops[i].status) {
+               if (map->map_ops[i].status == GNTST_okay)
+                       map->unmap_ops[i].handle = map->map_ops[i].handle;
+               else if (!err)
                        err = -EINVAL;
-                       continue;
-               }
 
                if (map->flags & GNTMAP_device_map)
                        map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr;
 
-               map->unmap_ops[i].handle = map->map_ops[i].handle;
-               if (use_ptemod)
-                       map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
+               if (use_ptemod) {
+                       if (map->kmap_ops[i].status == GNTST_okay)
+                               map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
+                       else if (!err)
+                               err = -EINVAL;
+               }
        }
        return err;
 }

diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 9bc5bc07d4d3f0f6ac119db1c511b03d347edc32..a9978350b45b0bf24290771568f03f1c7f93da3f 100644 (file)
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -157,6 +157,7 @@ gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
        map->flags = flags;
        map->ref = ref;
        map->dom = domid;
+       map->status = 1; /* arbitrary positive value */
 }
 
 static inline void