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In den letzten 30 Tagen veröffentlichte Sicherheitslücken für xen: 9. Davon im KEV-Katalog: 0.
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An issue was discovered in Xen through 4.14.x allowing x86 PV guest OS users to gain guest OS privileges by modifying kernel memory contents, because invalidation of TLB entries is mishandled during use of an INVLPG-like attack technique.
An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used
An issue was discovered in Xen through 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen's sanitization paths injects a #GP fault, and incorrectly delivers it twice to the guest. This causes the guest kernel to observe a kernel-privilege #GP fault (typically fatal) rather than a user-privilege #GP fault (usually converted into SIGSEGV/etc.). Malicious or buggy userspace can crash the guest kernel, resulting in a VM Denial of Service. All versions of Xen from 3.2 onwards are vulnerable. Only x86 systems are vulnerable. ARM pl
An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest (also operating on the timers) to release a lock that it didn't acquire. The most likely effect of the issue is a hang or crash of the hypervisor, i.e., a Denial of Service (DoS). All versions of Xen are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only x86 HVM guests can leverage the vulnerability. x86 PV and PVH cannot leverage the vulnerability. Only guests with more than
An issue was discovered in Xen through 4.14.x. An x86 PV guest can trigger a host OS crash when handling guest access to MSR_MISC_ENABLE. When a guest accesses certain Model Specific Registers, Xen first reads the value from hardware to use as the basis for auditing the guest access. For the MISC_ENABLE MSR, which is an Intel specific MSR, this MSR read is performed without error handling for a #GP fault, which is the consequence of trying to read this MSR on non-Intel hardware. A buggy or malicious PV guest administrator can crash Xen, resulting in a host Denial of Service. Only x86 systems are vulnerable. ARM systems are not vulnerable. Onl
An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions
An issue was discovered in Xen through 4.14.x. Out of bounds event channels are available to 32-bit x86 domains. The so called 2-level event channel model imposes different limits on the number of usable event channels for 32-bit x86 domains vs 64-bit or Arm (either bitness) ones. 32-bit x86 domains can use only 1023 channels, due to limited space in their shared (between guest and Xen) information structure, whereas all other domains can use up to 4095 in this model. The recording of the respective limit during domain initialization, however, has occurred at a time where domains are still deemed to be 64-bit ones, prior to actually honoring
An issue was discovered in Xen through 4.14.x. There are evtchn_reset() race conditions. Uses of EVTCHNOP_reset (potentially by a guest on itself) or XEN_DOMCTL_soft_reset (by itself covered by XSA-77) can lead to the violation of various internal assumptions. This may lead to out of bounds memory accesses or triggering of bug checks. In particular, x86 PV guests may be able to elevate their privilege to that of the host. Host and guest crashes are also possible, leading to a Denial of Service (DoS). Information leaks cannot be ruled out. All Xen versions from 4.5 onwards are vulnerable. Xen versions 4.4 and earlier are not vulnerable.
An issue was discovered in Xen through 4.14.x. There is mishandling of the constraint that once-valid event channels may not turn invalid. Logic in the handling of event channel operations in Xen assumes that an event channel, once valid, will not become invalid over the life time of a guest. However, operations like the resetting of all event channels may involve decreasing one of the bounds checked when determining validity. This may lead to bug checks triggering, crashing the host. An unprivileged guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xe
An issue was discovered in Xen through 4.14.x. The PCI passthrough code improperly uses register data. Code paths in Xen's MSI handling have been identified that act on unsanitized values read back from device hardware registers. While devices strictly compliant with PCI specifications shouldn't be able to affect these registers, experience shows that it's very common for devices to have out-of-spec "backdoor" operations that can affect the result of these reads. A not fully trusted guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. Privilege escalation and information leaks cannot be excluded. All ver
An issue was discovered in Xen through 4.13.x, allowing Intel guest OS users to gain privileges or cause a denial of service because of non-atomic modification of a live EPT PTE. When mapping guest EPT (nested paging) tables, Xen would in some circumstances use a series of non-atomic bitfield writes. Depending on the compiler version and optimisation flags, Xen might expose a dangerous partially written PTE to the hardware, which an attacker might be able to race to exploit. A guest administrator or perhaps even an unprivileged guest user might be able to cause denial of service, data corruption, or privilege escalation. Only systems using In
An issue was discovered in Xen through 4.13.x, allowing Arm guest OS users to cause a hypervisor crash because of a missing alignment check in VCPUOP_register_vcpu_info. The hypercall VCPUOP_register_vcpu_info is used by a guest to register a shared region with the hypervisor. The region will be mapped into Xen address space so it can be directly accessed. On Arm, the region is accessed with instructions that require a specific alignment. Unfortunately, there is no check that the address provided by the guest will be correctly aligned. As a result, a malicious guest could cause a hypervisor crash by passing a misaligned address. A malicious g
An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames
An issue was discovered in Xen through 4.13.x, allowing x86 HVM guest OS users to cause a hypervisor crash. An inverted conditional in x86 HVM guests' dirty video RAM tracking code allows such guests to make Xen de-reference a pointer guaranteed to point at unmapped space. A malicious or buggy HVM guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Xen versions from 4.8 onwards are affected. Xen versions 4.7 and earlier are not affected. Only x86 systems are affected. Arm systems are not affected. Only x86 HVM guests using shadow paging can leverage the vulnerability. In addition, there nee
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event-channel port allocation. The allocation of an event-channel port may fail for multiple reasons: (1) port is already in use, (2) the memory allocation failed, or (3) the port we try to allocate is higher than what is supported by the ABI (e.g., 2L or FIFO) used by the guest or the limit set by an administrator (max_event_channels in xl cfg). Due to the missing error checks, only (1) will be considered an error. All the other cases will provide a valid port and will result in a crash when trying to access
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of a bad error path in GNTTABOP_map_grant. Grant table operations are expected to return 0 for success, and a negative number for errors. Some misplaced brackets cause one error path to return 1 instead of a negative value. The grant table code in Linux treats this condition as success, and proceeds with incorrectly initialised state. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to map a grant, it hits the incorrect error path. This will crash a Linux based dom0 or backend doma
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of bad continuation handling in GNTTABOP_copy. Grant table operations are expected to return 0 for success, and a negative number for errors. The fix for CVE-2017-12135 introduced a path through grant copy handling where success may be returned to the caller without any action taken. In particular, the status fields of individual operations are left uninitialised, and may result in errant behaviour in the caller of GNTTABOP_copy. A buggy or malicious guest can construct its grant table in such a way that, when a backend domain tries to
An issue was discovered in xenoprof in Xen through 4.13.x, allowing guest OS users (with active profiling) to obtain sensitive information about other guests, cause a denial of service, or possibly gain privileges. For guests for which "active" profiling was enabled by the administrator, the xenoprof code uses the standard Xen shared ring structure. Unfortunately, this code did not treat the guest as a potential adversary: it trusts the guest not to modify buffer size information or modify head / tail pointers in unexpected ways. This can crash the host (DoS). Privilege escalation cannot be ruled out.
An issue was discovered in xenoprof in Xen through 4.13.x, allowing guest OS users (without active profiling) to obtain sensitive information about other guests. Unprivileged guests can request to map xenoprof buffers, even if profiling has not been enabled for those guests. These buffers were not scrubbed.
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the "critical" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a v
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