vulnerability

Amazon Linux AMI 2: CVE-2025-21779: Security patch for kernel (Multiple Advisories)

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
Feb 27, 2025
Added
Apr 30, 2025
Modified
May 13, 2025

Description

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

KVM: x86: Reject Hyper-V's SEND_IPI hypercalls if local APIC isn't in-kernel

Advertise support for Hyper-V's SEND_IPI and SEND_IPI_EX hypercalls if and
only if the local API is emulated/virtualized by KVM, and explicitly reject
said hypercalls if the local APIC is emulated in userspace, i.e. don't rely
on userspace to opt-in to KVM_CAP_HYPERV_ENFORCE_CPUID.

Rejecting SEND_IPI and SEND_IPI_EX fixes a NULL-pointer dereference if
Hyper-V enlightenments are exposed to the guest without an in-kernel local
APIC:

dump_stack+0xbe/0xfd
__kasan_report.cold+0x34/0x84
kasan_report+0x3a/0x50
__apic_accept_irq+0x3a/0x5c0
kvm_hv_send_ipi.isra.0+0x34e/0x820
kvm_hv_hypercall+0x8d9/0x9d0
kvm_emulate_hypercall+0x506/0x7e0
__vmx_handle_exit+0x283/0xb60
vmx_handle_exit+0x1d/0xd0
vcpu_enter_guest+0x16b0/0x24c0
vcpu_run+0xc0/0x550
kvm_arch_vcpu_ioctl_run+0x170/0x6d0
kvm_vcpu_ioctl+0x413/0xb20
__se_sys_ioctl+0x111/0x160
do_syscal1_64+0x30/0x40
entry_SYSCALL_64_after_hwframe+0x67/0xd1

Note, checking the sending vCPU is sufficient, as the per-VM irqchip_mode
can't be modified after vCPUs are created, i.e. if one vCPU has an
in-kernel local APIC, then all vCPUs have an in-kernel local APIC.

Solution(s)

amazon-linux-ami-2-upgrade-bpftoolamazon-linux-ami-2-upgrade-bpftool-debuginfoamazon-linux-ami-2-upgrade-kernelamazon-linux-ami-2-upgrade-kernel-debuginfoamazon-linux-ami-2-upgrade-kernel-debuginfo-common-aarch64amazon-linux-ami-2-upgrade-kernel-debuginfo-common-x86_64amazon-linux-ami-2-upgrade-kernel-develamazon-linux-ami-2-upgrade-kernel-headersamazon-linux-ami-2-upgrade-kernel-livepatch-5-10-236-227-928amazon-linux-ami-2-upgrade-kernel-livepatch-5-15-179-121-185amazon-linux-ami-2-upgrade-kernel-toolsamazon-linux-ami-2-upgrade-kernel-tools-debuginfoamazon-linux-ami-2-upgrade-kernel-tools-develamazon-linux-ami-2-upgrade-perfamazon-linux-ami-2-upgrade-perf-debuginfoamazon-linux-ami-2-upgrade-python-perfamazon-linux-ami-2-upgrade-python-perf-debuginfo
Title
NEW

Explore Exposure Command

Confidently identify and prioritize exposures from endpoint to cloud with full attack surface visibility and threat-aware risk context.