FreshPorts - VuXML

The Xen Project reports:

The XSA-29 fix introduced an insufficient check on XENMEM_exchange input, allowing the caller to drive hypervisor memory accesses outside of the guest provided input/output arrays.

A malicious or buggy 64-bit PV guest may be able to access all of system memory, allowing for all of privilege escalation, host crashes, and information leaks.

< 4.7.2_1

The Xen Project reports:

The x86 instruction CMPXCHG8B is supposed to ignore legacy operand size overrides; it only honors the REX.W override (making it CMPXCHG16B). So, the operand size is always 8 or 16. When support for CMPXCHG16B emulation was added to the instruction emulator, this restriction on the set of possible operand sizes was relied on in some parts of the emulation; but a wrong, fully general, operand size value was used for other parts of the emulation. As a result, if a guest uses a supposedly-ignored operand size prefix, a small amount of hypervisor stack data is leaked to the guests: a 96 bit leak to guests running in 64-bit mode; or, a 32 bit leak to other guests.

A malicious unprivileged guest may be able to obtain sensitive information from the host.

< 4.7.1_1

The Xen project reports multiple vulnerabilities.

< 4.7.2_6

The Xen Project reports:

Certain PV guest kernel operations (page table writes in particular) need emulation, and use Xen's general x86 instruction emulator. This allows a malicious guest kernel which asynchronously modifies its instruction stream to effect the clearing of EFLAGS.IF from the state used to return to guest context.

A malicious guest kernel administrator can cause a host hang or crash, resulting in a Denial of Service.

< 4.7.1_3

The Xen Project reports:

The typical behaviour of singlestepping exceptions is determined at the start of the instruction, with a #DB trap being raised at the end of the instruction. SYSCALL (and SYSRET, although we don't implement it) behave differently because the typical behaviour allows userspace to escalate its privilege. (This difference in behaviour seems to be undocumented.) Xen wrongly raised the exception based on the flags at the start of the instruction.

Guest userspace which can invoke the instruction emulator can use this flaw to escalate its privilege to that of the guest kernel.

< 4.7.1_2