xen/grant-table: add gnttab_try_end_foreign_access()

stable inclusion
from stable-v5.10.105
commit 3d81e85f30a8f712c3e4f2a507553d9063a20ed6
bugzilla: 186480 https://gitee.com/src-openeuler/kernel/issues/I50WBV
CVE: CVE-2022-23036, CVE-2022-23038

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d81e85f30a8f712c3e4f2a507553d9063a20ed6



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

Commit 6b1775f2 upstream.

Add a new grant table function gnttab_try_end_foreign_access(), which
will remove and free a grant if it is not in use.

Its main use case is to either free a grant if it is no longer in use,
or to take some other action if it is still in use. This other action
can be an error exit, or (e.g. in the case of blkfront persistent grant
feature) some special handling.

This is CVE-2022-23036, CVE-2022-23038 / part of XSA-396.

Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.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>