x86: DMs may cause mem leak by IRQ binding

ISSUE DESCRIPTION When guests are terminated, various pieces of cleanup need carrying out. The cleaning up of PCI devices which were assigned to guests, and the associated removal of tracking structures for IRQs used by the devices occurs relatively early in the process. Unfortunately after that...

Linux xen-netfront: backend can crash guest via malformed RX packets

ISSUE DESCRIPTION If a RX packet sent from the networking backend to the Linux xen-netfront driver is split into multiple slots and the first slot is shorter than an Ethernet header, a BUG will crash the guest. This is a backend induced Denial of Service DoS. IMPACT A malicious network backend ca...

tapdisk: Out-of-bounds access in tap_ctl_connect_xenblkif()

ISSUE DESCRIPTION Tapdisk is a userspace xen-blkback implementation used by the XAPI toolstack. During connection, multi-page rings may be negotiated between the frontend and backend. Tapdisk had no boundary check on the size requested by the frontend, and assumed it did not exceed 8. IMPACT A...

gnttab: cache-flush handling may cause page reference leak

ISSUE DESCRIPTION With its original introduction, GNTTABcacheflush was made available uniformly. XSA-232 CVE-2017-14318 then covered an omitted NULL pointer check, yet the addition of that check failed to adjust the subsequent error path. That error path fails to drop a page reference in case the...

Arm: multiple issues with GNTTABOP_cache_flush

ISSUE DESCRIPTION 1 XSA-437 CVE-2023-34321 addressed issues with overflows in calculations involved in guests flushing caches through GNTTABOPcacheflush. Unfortunately the fix there introduced a calculation which may underflow, resulting in a loop which would - at least on 64-bit Arm - take...

x86: XPTI may break on huge-memory systems

ISSUE DESCRIPTION XPTI Xen Page Table Isolation was introduced to mitigate Meltdown CVE-2017-5754, one aspect of XSA-254. This involves copying 64-bit PV guest page table entries from guest-chosen root page tables to the Xen- chosen one which is in actual use by hardware. To read the guest root...

Xenstore: Guests can crash xenstored during Live Update

ISSUE DESCRIPTION During Xenstore live update the state record for a Xenstore watch with specified watch depth is written with two bytes missing. This results in an inconsistent state when reading the state back in the new Xenstore, causing a crash of Xenstore or wrong Xenstore data. IMPACT An...

VMX: VMentry failure with branch tracing and blocked states

ISSUE DESCRIPTION For XSA-308 logic was introduced, as VMX VMEntry checks do not like the exact combination of state which occurs when DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in. The resulting VMEntry failure is...

grant-table: double version change race

ISSUE DESCRIPTION XSA-501 was about issues with v1 - v2 and v2 - v1 changes racing certain other grant table operations. Sadly a v2 - v1 - v2 change has yet another effect which wasn't accounted for: During the first change, status pages would be freed. During the second change they would be...

x86/AMD: ineffectual Zenbleed workaround

ISSUE DESCRIPTION The workaround for XSA-433 Zenbleed, CVE-2023-20593 was later re-worked to better integrate with other manipulations of the same MSR. In this rework an inverted conditional was introduced, resulting in the workaround to not be applied when needed and vice versa. For more details...