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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.4280 linux-4.9 security update 14 November 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: linux-4.9 Publisher: Debian Operating System: Debian GNU/Linux 8 Debian GNU/Linux 9 Impact/Access: Root Compromise -- Existing Account Access Privileged Data -- Existing Account Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2019-11135 CVE-2019-0155 CVE-2019-0154 CVE-2018-12207 Reference: ASB-2019.0330 ASB-2019.0313 ASB-2019.0138 ESB-2019.4273 ESB-2019.4272 Original Bulletin: https://security-tracker.debian.org/tracker/DLA-1990-1 - --------------------------BEGIN INCLUDED TEXT-------------------- Package : linux-4.9 Version : 4.9.189-3+deb9u2~deb8u1 CVE ID : CVE-2018-12207 CVE-2019-0154 CVE-2019-0155 CVE-2019-11135 Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service, or information leak. CVE-2018-12207 It was discovered that on Intel CPUs supporting hardware virtualisation with Extended Page Tables (EPT), a guest VM may manipulate the memory management hardware to cause a Machine Check Error (MCE) and denial of service (hang or crash). The guest triggers this error by changing page tables without a TLB flush, so that both 4 KB and 2 MB entries for the same virtual address are loaded into the instruction TLB (iTLB). This update implements a mitigation in KVM that prevents guest VMs from loading 2 MB entries into the iTLB. This will reduce performance of guest VMs. Further information on the mitigation can be found at <https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/multihit.html> or in the linux-doc-4.9 package. Intel's explanation of the issue can be found at <https://software.intel.com/security-software-guidance/insights/deep-dive-machine-check-error-avoidance-page-size-change-0>;. CVE-2019-0154 Intel discovered that on their 8th and 9th generation GPUs, reading certain registers while the GPU is in a low-power state can cause a system hang. A local user permitted to use the GPU can use this for denial of service. This update mitigates the issue through changes to the i915 driver. The affected chips (gen8 and gen9) are listed at <https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units#Gen8>;. CVE-2019-0155 Intel discovered that their 9th generation and newer GPUs are missing a security check in the Blitter Command Streamer (BCS). A local user permitted to use the GPU could use this to access any memory that the GPU has access to, which could result in a denial of service (memory corruption or crash), a leak of sensitive information, or privilege escalation. This update mitigates the issue by adding the security check to the i915 driver. The affected chips (gen9 onward) are listed at <https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units#Gen9>;. CVE-2019-11135 It was discovered that on Intel CPUs supporting transactional memory (TSX), a transaction that is going to be aborted may continue to execute speculatively, reading sensitive data from internal buffers and leaking it through dependent operations. Intel calls this "TSX Asynchronous Abort" (TAA). For CPUs affected by the previously published Microarchitectural Data Sampling (MDS) issues (CVE-2018-12126, CVE-2018-12127, CVE-2018-12130, CVE-2019-11091), the existing mitigation also mitigates this issue. For processors that are vulnerable to TAA but not MDS, this update disables TSX by default. This mitigation requires updated CPU microcode. An updated intel-microcode package (only available in Debian non-free) will be provided via a future DLA. The updated CPU microcode may also be available as part of a system firmware ("BIOS") update. Further information on the mitigation can be found at <https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html> or in the linux-doc-4.9 package. Intel's explanation of the issue can be found at <https://software.intel.com/security-software-guidance/insights/deep-dive-intel-transactional-synchronization-extensions-intel-tsx-asynchronous-abort>;. For Debian 8 "Jessie", these problems have been fixed in version 4.9.189-3+deb9u2~deb8u1. We recommend that you upgrade your linux-4.9 packages. Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS - -- Ben Hutchings - Debian developer, member of kernel, installer and LTS teams - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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