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Xen/gntdev: correct error checking in gntdev_map_grant_pages()

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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>
This commit is contained in:
Jan Beulich 2021-02-15 08:52:27 +01:00 committed by Juergen Gross
parent dbe5283605
commit ebee0eab08
2 changed files with 10 additions and 8 deletions
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17
drivers/xen/gntdev.c
View File

@ -334,21 +334,22 @@ 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;
}

1
include/xen/grant_table.h
View File

@ -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