xen/blkfront: don't use gnttab_query_foreign_access() for mapped status

stable inclusion
from stable-v5.10.105
commit 96219af4e504d0e96a231a0ba86062ec5b3af979
bugzilla: 186480 https://gitee.com/src-openeuler/kernel/issues/I50WBV
CVE: CVE-2022-23036

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=96219af4e504d0e96a231a0ba86062ec5b3af979



--------------------------------

Commit abf1fd59 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>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>