漏洞标题
64位元 PV guests 的顶级阴影参考在弹出过早了。
漏洞描述信息
为了迁移以及绕过不知道L1TF的内核(见XSA-273), PV虚拟机可以运行在阴影页映射模式中。由于PV虚拟机运行时Xen需要被映射，所以Xen和阴影PV虚拟机直接运行相应的阴影页表。对于64位PV虚拟机，这意味着运行在 guest 根页表的阴影中。
在处理与域相关的阴影池内存不足时，页面表的阴影可能会被撕毁。这个撕毁可能包括当前运行在CPU上的阴影根页表。尽管存在一种预防性措施，旨在防止底层活动页表的撕毁，但该预防性措施覆盖的时间窗口不足以满足要求。
CVSS信息
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
漏洞类别
未加控制的资源消耗(资源穷尽)
漏洞标题
top-level shadow reference dropped too early for 64-bit PV guests
漏洞描述信息
For migration as well as to work around kernels unaware of L1TF (see
XSA-273), PV guests may be run in shadow paging mode. Since Xen itself
needs to be mapped when PV guests run, Xen and shadowed PV guests run
directly the respective shadow page tables. For 64-bit PV guests this
means running on the shadow of the guest root page table.
In the course of dealing with shortage of memory in the shadow pool
associated with a domain, shadows of page tables may be torn down. This
tearing down may include the shadow root page table that the CPU in
question is presently running on. While a precaution exists to
supposedly prevent the tearing down of the underlying live page table,
the time window covered by that precaution isn't large enough.
CVSS信息
N/A
漏洞类别
N/A
漏洞标题
Xen 安全漏洞
漏洞描述信息
Xen是英国剑桥（Cambridge）大学的一款开源的虚拟机监视器产品。该产品能够使不同和不兼容的操作系统运行在同一台计算机上，并支持在运行时进行迁移，保证正常运行并且避免宕机。 Xen存在安全漏洞，该漏洞源于在处理shadow memory不足过程中与域相关联的页表的shadow可能会被拆除，这拆除可能包括CPU所在的shadow page。
CVSS信息
N/A
漏洞类别
其他