Affected: Alpaquita:23: linux-lts, Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

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…

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…

kernel: use after free in i2c kernel: bluetooth: BR/EDR Bluetooth Impersonation Attacks (BIAS) kernel: hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations kernel: asix: fix uninit-value in asix_mdio_read() kernel: tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc kernel: hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field kernel: hwmon: (w83791d) Fix NULL pointer dereference by removing unnecessary structure field kernel: powerpc/64s: fix program check interrupt emergency stack path kernel: powerpc/64s: Fix unrecoverable MCE calling async handler from NMI kernel: lib/generic-radix-tree.c: Don't overflow in peek() kernel: powerpc/smp: do not decrement idle task preempt count in CPU offline kernel: can: isotp: isotp_sendmsg(): add result check for wait_event_interruptible() kernel: usbnet: sanity check for maxpacket kernel: nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells kernel: aio: fix use-after-free due to missing POLLFREE handling kernel: powerpc/pseries: Fix potential memleak in papr_get_attr() kernel: of: fdt: fix off-by-one error in unflatten_dt_nodes() kernel: thermal/int340x_thermal: handle data_vault when the value is ZERO_SIZE_PTR kernel: vt_ioctl: fix array_index_nospec in vt_setactivate kernel: bpf: Fix crash due to out of bounds access into reg2btf_ids. kernel: lz4: fix LZ4_decompress_safe_partial read out of bound kernel: x86/mce: Work around an erratum on fast string copy instructions…

Security update for the Linux Kernel

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 84 more

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 by us…

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen oder sonstige Auswirkungen zu verursachen.