-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 - ------------------------------------------------------------------------- Debian Security Advisory DSA-4564-1 security@xxxxxxxxxx https://www.debian.org/security/ Ben Hutchings November 12, 2019 https://www.debian.org/security/faq - ------------------------------------------------------------------------- Package : linux 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 or linux-doc-4.19 package. A qemu update adding support for the PSCHANGE_MC_NO feature, which allows to disable iTLB Multihit mitigations in nested hypervisors will be provided via DSA 4566-1. 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 DSA 4565-1. 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 or linux-doc-4.19 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 the oldstable distribution (stretch), these problems have been fixed in version 4.9.189-3+deb9u2. For the stable distribution (buster), these problems have been fixed in version 4.19.67-2+deb10u2. We recommend that you upgrade your linux packages. For the detailed security status of linux please refer to its security tracker page at: https://security-tracker.debian.org/tracker/linux Further information about Debian Security Advisories, how to apply these updates to your system and frequently asked questions can be found at: https://www.debian.org/security/ Mailing list: debian-security-announce@xxxxxxxxxxxxxxxx -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEERkRAmAjBceBVMd3uBUy48xNDz0QFAl3LBMVfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldDQ2 NDQ0MDk4MDhDMTcxRTA1NTMxRERFRTA1NENCOEYzMTM0M0NGNDQACgkQBUy48xND z0RtSg//aBsENrrs5mbCKYxt6Lm1hVdxdmz+9TbgZkxU+lQ0XEfge4wQUCa8KhJh os4qGuDXh5q/2VkNMa+cUCyHCyxxl3qv4rCsm+MxG1Rd4Hy4JoKt4heJgi5hXW9A qhOQ5+rHb0OeoPM9BCduTi37h+mLS4ItRz30n3+3B2+VC0tj+iV2nOZJmC0WMEiq LrqeDm39pa6DqKBAExdYT/TCyKLsngMHoIGorWVPXdJP1/xmrH2gU0W3L7k5KJPz apeCi4E3H9bjRh8Be5SeT3zDoEaiiNn/sHHkLDeAryFMuwilekxFaYocbW/0CEIH kWRMkC+uq1KfQfBDSxIOsH8yq8n+zQ12XJ0YiiqEKg6ErabWz5rCaVHyPWvdh0Ny mezs99PkQ7mUkjAUVzIfz2Rq6VByOCdfuT/GvPL7rUtIJYRdqYkWBI8t/hVlrnDq yR+X7vQZWm5wb3+Jiz/sA6TqgDvKSgk1+tUfBmqI9sh1wWNKSSYee0b81BLLubs3 IInPlgW2Lp+IsA3CVKKQNTNMWZkuNyPZH2UGpZV45otazcLPrrdNtt52x4gvIJ/W lizVpb2BOpTpoeEXNYlEDCjwcrW9f1FkVztwMgz3J6eb9pHjieFuGO9vOxcP7li3 FNJbGhaUUZa8BfjsQgBwFSwVXRr212zK9yv0UHnLRJo4l0I3xC0= =YZWL -----END PGP SIGNATURE-----
