Juergen Gross 423a3a50dc xen/blkfront: don't use gnttab_query_foreign_access() for mapped status
Commit abf1fd5919d6238ee3bc5eb4a9b6c3947caa6638 upstream.

It isn't enough to check whether a grant is still being in use by
calling gnttab_query_foreign_access(), as a mapping could be realized
by the other side just after having called that function.

In case the call was done in preparation of revoking a grant it is
better to do so via gnttab_end_foreign_access_ref() and check the
success of that operation instead.

For the ring allocation use alloc_pages_exact() in order to avoid
high order pages in case of a multi-page ring.

If a grant wasn't unmapped by the backend without persistent grants
being used, set the device state to "error".

This is CVE-2022-23036 / part of XSA-396.

Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-11 10:15:12 +01:00
..
2020-02-24 08:34:53 +01:00
2021-09-22 11:47:46 +02:00
2018-11-13 11:08:20 -08:00
2018-06-12 16:19:22 -07:00