CVE-2019-18422

An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service or gain privileges by leveraging the erroneous enabling of interrupts. Interrupts are unconditionally unmasked in exception handlers. When an exception occurs on an ARM system which is handled without changing processor level, some interrupts are unconditionally enabled during exception entry. So exceptions which occur when interrupts are masked will effectively unmask the interrupts. A malicious guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified.

An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service or gain privileges by leveraging the erroneous enabling of interrupts. Interrupts are unconditionally unmasked in exception handlers. When an exception occurs on an ARM system which is handled without changing processor level, some interrupts are unconditionally enabled during exception entry. So exceptions which occur when interrupts are masked will effectively unmask the interrupts. A malicious guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified.

• Updated from 4.12.0 to 4.12.1
• Device quarantine for alternate pci assignment methods [XSA-306]
• x86: Machine Check Error on Page Size Change DoS [XSA-304, CVE-2018-12207]
• TSX Asynchronous Abort speculative side channel [XSA-305, CVE-2019-11135]
• VCPUOP_initialise DoS [XSA-296, CVE-2019-18420] (rhbz#1771368)
• missing descriptor table limit checking in x86 PV emulation [XSA-298, CVE-2019-18425] (rhbz#1771341)
• Issues with restartable PV type change operations [XSA-299, CVE-2019-18421] (rhbz#1767726)
• add-to-physmap can be abused to DoS Arm hosts [XSA-301, CVE-2019-18423] (rhbz#1771345)
• passed through PCI devices may corrupt host memory after deassignment [XSA-302, CVE-2019-18424] (rhbz#1767731)
• ARM: Interrupts are unconditionally unmasked in exception handlers [XSA-303, CVE-2019-18422] (rhbz#1771443)
• Unlimited Arm Atomics Operations [XSA-295, CVE-2019-17349, CVE-2019-17350] (rhbz#1720760)
• fix HVM DomU boot on some chipsets
• adjust grub2 workaround

This update for xen fixes the following issues:

• CVE-2018-12207: Untrusted virtual machines on Intel CPUs could exploit a race condition in the Instruction Fetch Unit of the Intel CPU to cause a Machine Exception during Page Size Change, causing the CPU core to be non-functional. (bsc#1155945)
• CVE-2019-11135: Aborting an asynchronous TSX operation on Intel CPUs with Transactional Memory support could be used to facilitate sidechannel information leaks out of microarchitectural buffers, similar to the previously described 'Microarchitectural Data Sampling' attack. (bsc#1152497).
• CVE-2019-18423: A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). (bsc#1154460).
• CVE-2019-18422: A malicious ARM guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified. (bsc#1154464)
• CVE-2019-18424: An untrusted domain with access to a physical device can DMA into host memory, leading to privilege escalation. (bsc#1154461).
• CVE-2019-18421: A malicious PV guest administrator may have been able to escalate their privilege to that of the host. (bsc#1154458).
• CVE-2019-18425: 32-bit PV guest user mode could elevate its privileges to that of the guest kernel. (bsc#1154456).
• CVE-2019-18420: Malicious x86 PV guests may have caused a hypervisor crash, resulting in a Denial of Service (Dos). (bsc#1154448)
• Upstream bug fixes (bsc#1027519)

This update for xen fixes the following issues:

• CVE-2019-19581: Fixed a potential out of bounds on 32-bit Arm (bsc#1158003 XSA-307).
• CVE-2019-19582: Fixed a potential infinite loop when x86 accesses to bitmaps with a compile time known size of 64 (bsc#1158003 XSA-307).
• CVE-2019-19583: Fixed improper checks which could have allowed HVM/PVH guest userspace code to crash the guest,leading to a guest denial of service (bsc#1158004 XSA-308).
• CVE-2019-19578: Fixed an issue where a malicious or buggy PV guest could have caused hypervisor crash resulting in denial of service affecting the entire host (bsc#1158005 XSA-309).
• CVE-2019-19580: Fixed a privilege escalation where a malicious PV guest administrator could have been able to escalate their privilege to that of the host (bsc#1158006 XSA-310).
• CVE-2019-19577: Fixed an issue where a malicious guest administrator could have caused Xen to access data structures while they are being modified leading to a crash (bsc#1158007 XSA-311).
• CVE-2019-19579: Fixed a privilege escaltion where an untrusted domain with access to a physical device can DMA into host memory (bsc#1157888 XSA-306).
• CVE-2019-18420: Malicious x86 PV guests may have caused a hypervisor crash, resulting in a denial of service (bsc#1154448 XSA-296)
• CVE-2019-18425: 32-bit PV guest user mode could elevate its privileges to that of the guest kernel. (bsc#1154456 XSA-298).
• CVE-2019-18421: A malicious PV guest administrator may have been able to escalate their privilege to that of the host. (bsc#1154458 XSA-299).
• CVE-2019-18423: A malicious guest administrator may cause a hypervisor crash, resulting in a denial of service (bsc#1154460 XSA-301).
• CVE-2019-18422: A malicious ARM guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified. (bsc#1154464 XSA-303)
• CVE-2019-18424: An untrusted domain with access to a physical device can DMA into host memory, leading to privilege escalation. (bsc#1154461 XSA-302).
• CVE-2018-12207: Untrusted virtual machines on Intel CPUs could exploit a race condition in the Instruction Fetch Unit of the Intel CPU to cause a Machine Exception during Page Size Change, causing the CPU core to be non-functional. (bsc#1155945 XSA-304)
• CVE-2019-11135: Aborting an asynchronous TSX operation on Intel CPUs with Transactional Memory support could be used to facilitate sidechannel information leaks out of microarchitectural buffers, similar to the previously described 'Microarchitectural Data Sampling' attack. (bsc#1152497 XSA-305).

This update for xen fixes the following issues:

• CVE-2019-19581: Fixed a potential out of bounds on 32-bit Arm (bsc#1158003 XSA-307).
• CVE-2019-19582: Fixed a potential infinite loop when x86 accesses to bitmaps with a compile time known size of 64 (bsc#1158003 XSA-307).
• CVE-2019-19583: Fixed improper checks which could have allowed HVM/PVH guest userspace code to crash the guest,leading to a guest denial of service (bsc#1158004 XSA-308).
• CVE-2019-19578: Fixed an issue where a malicious or buggy PV guest could have caused hypervisor crash resulting in denial of service affecting the entire host (bsc#1158005 XSA-309).
• CVE-2019-19580: Fixed a privilege escalation where a malicious PV guest administrator could have been able to escalate their privilege to that of the host (bsc#1158006 XSA-310).
• CVE-2019-19577: Fixed an issue where a malicious guest administrator could have caused Xen to access data structures while they are being modified leading to a crash (bsc#1158007 XSA-311).
• CVE-2019-19579: Fixed a privilege escaltion where an untrusted domain with access to a physical device can DMA into host memory (bsc#1157888 XSA-306).
• CVE-2019-18423: A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS) (bsc#1154460 XSA-301).
• CVE-2019-18422: A malicious ARM guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified. (bsc#1154464 XSA-303)

This update for xen fixes the following issues:

• CVE-2019-19581: Fixed a potential out of bounds on 32-bit Arm (bsc#1158003 XSA-307).
• CVE-2019-19582: Fixed a potential infinite loop when x86 accesses to bitmaps with a compile time known size of 64 (bsc#1158003 XSA-307).
• CVE-2019-19583: Fixed improper checks which could have allowed HVM/PVH guest userspace code to crash the guest,leading to a guest denial of service (bsc#1158004 XSA-308).
• CVE-2019-19578: Fixed an issue where a malicious or buggy PV guest could have caused hypervisor crash resulting in denial of service affecting the entire host (bsc#1158005 XSA-309).
• CVE-2019-19580: Fixed a privilege escalation where a malicious PV guest administrator could have been able to escalate their privilege to that of the host (bsc#1158006 XSA-310).
• CVE-2019-19577: Fixed an issue where a malicious guest administrator could have caused Xen to access data structures while they are being modified leading to a crash (bsc#1158007 XSA-311).
• CVE-2019-19579: Fixed a privilege escaltion where an untrusted domain with access to a physical device can DMA into host memory (bsc#1157888 XSA-306).
• CVE-2019-18423: A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). (bsc#1154460).
• CVE-2019-18424: An untrusted domain with access to a physical device can DMA into host memory, leading to privilege escalation. (bsc#1154461).
• CVE-2019-18422: A malicious ARM guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified. (bsc#1154464)