Description (CNA)
The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative Return Stack Overflow) are not IRQ-safe. It was believed that the mitigations always operated in contexts with IRQs disabled. However, the original XSA-254 fix for Meltdown (XPTI) deliberately left interrupts enabled on two entry paths; one unconditionally, and one conditionally on whether XPTI was active. As BTC/SRSO and Meltdown affect different CPU vendors, the mitigations are not active together by default. Therefore, there is a race condition whereby a malicious PV guest can bypass BTC/SRSO protections and launch a BTC/SRSO attack against Xen.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Xen / Xen | unknown consult Xen advisory XSA-446 |
CWE
No CWE identifiers supplied.
References
ADP enrichment
No English description supplied.
No English description supplied.
No references supplied.