CVE-2024-26992 — KVM: x86/pmu: Disable support for adaptive PEBS

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86/pmu: Disable support for adaptive PEBS

Drop support for virtualizing adaptive PEBS, as KVM's implementation is architecturally broken without an obvious/easy path forward, and because exposing adaptive PEBS can leak host LBRs to the guest, i.e. can leak host kernel addresses to the guest.

Bug #1 is that KVM doesn't account for the upper 32 bits of IA32_FIXED_CTR_CTRL when (re)programming fixed counters, e.g fixed_ctrl_field() drops the upper bits, reprogram_fixed_counters() stores local variables as u8s and truncates the upper bits too, etc.

Bug #2 is that, because KVM _always_ sets precise_ip to a non-zero value for PEBS events, perf will _always_ generate an adaptive record, even if the guest requested a basic record. Note, KVM will also enable adaptive PEBS in individual *counter*, even if adaptive PEBS isn't exposed to the guest, but this is benign as MSR_PEBS_DATA_CFG is guaranteed to be zero, i.e. the guest will only ever see Basic records.

Bug #3 is in perf. intel_pmu_disable_fixed() doesn't clear the upper bits either, i.e. leaves ICL_FIXED_0_ADAPTIVE set, and intel_pmu_enable_fixed() effectively doesn't clear ICL_FIXED_0_ADAPTIVE either. I.e. perf _always_ enables ADAPTIVE counters, regardless of what KVM requests.

Bug #4 is that adaptive PEBS *might* effectively bypass event filters set by the host, as "Updated Memory Access Info Group" records information that might be disallowed…

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities

Affected: Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-azure, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-intel, Ubuntu:24.04:LTS: linux-lowlatency, Ubuntu:24.04:LTS: linux-oem-6.8, Ubuntu:24.04:LTS: linux-raspi

It was discovered that a race condition existed in the Bluetooth subsystem in the Linux kernel when modifying certain settings values through debugfs. A privileged local attacker could use this to cause a denial of service. (CVE-2024-24857, CVE-2024-24858, CVE-2024-24859)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Compute Acceleration Framework; - Accessibility subsystem; - Android drivers; - Drivers core; - Bluetooth drivers; - Clock framework and drivers; - Data acquisition framework and drivers; - Cryptographic API; - Buffer Sharing and Synchronization framework; - GPU drivers; - On-Chip Interconnect management framework; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - VMware VMCI Driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - Device tree and open firmware driver; - Chrome hardware platform drivers; - i.MX PM domains; - TI SCI PM domains driver; - S/390 drivers; - SCSI drivers; - SPI subsystem; - Thermal drivers; - TTY drivers; - USB subsystem; - Framebuffer layer; - BTRFS file system; - Network file system server daemon; - NILFS2 file system; - File systems infrastructure; - Pstore file system; - SMB…

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CVE-2024-26992 — KVM: x86/pmu: Disable support for adaptive PEBS

USN-6893-1 — linux, linux-azure, linux-gcp, linux-ibm, linux-intel, linux-lowlatency, linux-oem-6.8, linux-raspi vulnerabilities