CVE-2024-45005: Vulnerability in Linux Linux

Severity: highType: vulnerabilityCVE-2024-45005

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: fix validity interception issue when gisa is switched off We might run into a SIE validity if gisa has been disabled either via using kernel parameter "kvm.use_gisa=0" or by setting the related sysfs attribute to N (echo N >/sys/module/kvm/parameters/use_gisa). The validity is caused by an invalid value in the SIE control block's gisa designation. That happens because we pass the uninitialized gisa origin to virt_to_phys() before writing it to the gisa designation. To fix this we return 0 in kvm_s390_get_gisa_desc() if the origin is 0. kvm_s390_get_gisa_desc() is used to determine which gisa designation to set in the SIE control block. A value of 0 in the gisa designation disables gisa usage. The issue surfaces in the host kernel with the following kernel message as soon a new kvm guest start is attemted. kvm: unhandled validity intercept 0x1011 WARNING: CPU: 0 PID: 781237 at arch/s390/kvm/intercept.c:101 kvm_handle_sie_intercept+0x42e/0x4d0 [kvm] Modules linked in: vhost_net tap tun xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT xt_tcpudp nft_compat x_tables nf_nat_tftp nf_conntrack_tftp vfio_pci_core irqbypass vhost_vsock vmw_vsock_virtio_transport_common vsock vhost vhost_iotlb kvm nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables sunrpc mlx5_ib ib_uverbs ib_core mlx5_core uvdevice s390_trng eadm_sch vfio_ccw zcrypt_cex4 mdev vfio_iommu_type1 vfio sch_fq_codel drm i2c_core loop drm_panel_orientation_quirks configfs nfnetlink lcs ctcm fsm dm_service_time ghash_s390 prng chacha_s390 libchacha aes_s390 des_s390 libdes sha3_512_s390 sha3_256_s390 sha512_s390 sha256_s390 sha1_s390 sha_common dm_mirror dm_region_hash dm_log zfcp scsi_transport_fc scsi_dh_rdac scsi_dh_emc scsi_dh_alua pkey zcrypt dm_multipath rng_core autofs4 [last unloaded: vfio_pci] CPU: 0 PID: 781237 Comm: CPU 0/KVM Not tainted 6.10.0-08682-gcad9f11498ea #6 Hardware name: IBM 3931 A01 701 (LPAR) Krnl PSW : 0704c00180000000 000003d93deb0122 (kvm_handle_sie_intercept+0x432/0x4d0 [kvm]) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 Krnl GPRS: 000003d900000027 000003d900000023 0000000000000028 000002cd00000000 000002d063a00900 00000359c6daf708 00000000000bebb5 0000000000001eff 000002cfd82e9000 000002cfd80bc000 0000000000001011 000003d93deda412 000003ff8962df98 000003d93de77ce0 000003d93deb011e 00000359c6daf960 Krnl Code: 000003d93deb0112: c020fffe7259 larl %r2,000003d93de7e5c4 000003d93deb0118: c0e53fa8beac brasl %r14,000003d9bd3c7e70 #000003d93deb011e: af000000 mc 0,0 >000003d93deb0122: a728ffea lhi %r2,-22 000003d93deb0126: a7f4fe24 brc 15,000003d93deafd6e 000003d93deb012a: 9101f0b0 tm 176(%r15),1 000003d93deb012e: a774fe48 brc 7,000003d93deafdbe 000003d93deb0132: 40a0f0ae sth %r10,174(%r15) Call Trace: [<000003d93deb0122>] kvm_handle_sie_intercept+0x432/0x4d0 [kvm] ([<000003d93deb011e>] kvm_handle_sie_intercept+0x42e/0x4d0 [kvm]) [<000003d93deacc10>] vcpu_post_run+0x1d0/0x3b0 [kvm] [<000003d93deaceda>] __vcpu_run+0xea/0x2d0 [kvm] [<000003d93dead9da>] kvm_arch_vcpu_ioctl_run+0x16a/0x430 [kvm] [<000003d93de93ee0>] kvm_vcpu_ioctl+0x190/0x7c0 [kvm] [<000003d9bd728b4e>] vfs_ioctl+0x2e/0x70 [<000003d9bd72a092>] __s390x_sys_ioctl+0xc2/0xd0 [<000003d9be0e9222>] __do_syscall+0x1f2/0x2e0 [<000003d9be0f9a90>] system_call+0x70/0x98 Last Breaking-Event-Address: [<000003d9bd3c7f58>] __warn_printk+0xe8/0xf0

AI Analysis

Technical Summary

CVE-2024-45005 is a vulnerability identified in the Linux kernel's KVM (Kernel-based Virtual Machine) subsystem specifically affecting the s390 architecture, which is IBM's mainframe platform. The issue arises when the GISA (Guest Instruction Steal Address) feature is disabled either through the kernel parameter "kvm.use_gisa=0" or by setting the corresponding sysfs attribute to 'N'. Under these conditions, an uninitialized value is passed to the SIE (Start Interpretive Execution) control block's GISA designation field. This uninitialized value leads to an invalid state causing a 'validity interception' error during the start of a new KVM guest. The kernel logs a warning with messages such as "kvm: unhandled validity intercept 0x1011" and a stack trace pointing to the kvm_handle_sie_intercept function. The root cause is that the function kvm_s390_get_gisa_desc() does not properly handle the case when the origin is zero, leading to passing an invalid physical address to virt_to_phys(). The patch fixes this by returning zero if the origin is zero, effectively disabling GISA usage safely. This vulnerability affects Linux kernel versions containing the specified commit hashes and impacts environments running KVM on s390 hardware with GISA disabled. Although no known exploits are reported in the wild, the issue can cause guest startup failures and kernel warnings, potentially leading to denial of service or instability in virtualized mainframe environments. The vulnerability is specific to the s390 KVM implementation and does not affect other architectures or virtualization platforms.

Potential Impact

For European organizations utilizing IBM mainframe systems running Linux with KVM virtualization, particularly those disabling GISA for performance or compatibility reasons, this vulnerability could cause guest virtual machines to fail to start or operate correctly. This can lead to service disruptions in critical enterprise workloads, especially in sectors like banking, government, and large-scale manufacturing where mainframes are prevalent. The kernel warnings and intercept errors may also complicate troubleshooting and system stability. While the vulnerability does not appear to allow privilege escalation or remote code execution, the denial of service impact on virtualized environments can affect availability of critical applications. Organizations relying on s390 KVM guests for production workloads may experience operational interruptions until patched. Given the specialized nature of the affected platform, the impact is limited to environments with this specific configuration but can be significant within those contexts.

Mitigation Recommendations

European organizations running Linux KVM on s390 hardware should immediately audit their kernel parameters and sysfs settings to check if GISA is disabled (kvm.use_gisa=0 or /sys/module/kvm/parameters/use_gisa set to 'N'). If so, they should plan to update their Linux kernel to a version containing the fix for CVE-2024-45005 as soon as it becomes available. In the interim, consider enabling GISA if compatible with workloads to avoid triggering the vulnerability. Additionally, monitor kernel logs for the specific intercept error messages to detect attempts to start guests that may be affected. Testing patches in staging environments before production deployment is recommended due to the critical nature of mainframe workloads. Engage with Linux distribution vendors and IBM support channels for guidance and timely patch releases. Avoid disabling GISA unless absolutely necessary, and ensure virtualization configurations adhere to best practices for s390 KVM deployments.