From: Juergen Gross <jgross@suse.com> stable inclusion from linux-4.19.234 commit 62a696c15cfcfd32527f81ca3d94f2bde57475dc -------------------------------- Commit 33172ab50a53578a95691310f49567c9266968b0 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_try_end_foreign_access() and check the success of that operation instead. This is 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: Yongqiang Liu <liuyongqiang13@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> --- drivers/scsi/xen-scsifront.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c index 61389bdc7926..a1d822ae9fca 100644 --- a/drivers/scsi/xen-scsifront.c +++ b/drivers/scsi/xen-scsifront.c @@ -233,12 +233,11 @@ static void scsifront_gnttab_done(struct vscsifrnt_info *info, return; for (i = 0; i < shadow->nr_grants; i++) { - if (unlikely(gnttab_query_foreign_access(shadow->gref[i]))) { + if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) { shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME "grant still in use by backend\n"); BUG(); } - gnttab_end_foreign_access(shadow->gref[i], 0, 0UL); } kfree(shadow->sg); -- 2.22.0