{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89513", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.717Z", "datePublished": "2026-09-11T19:43:57.960Z", "dateUpdated": "2026-10-19T08:48:04.610Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:04.610Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRISC-V: KVM: Fix PMU event info array size overflow\n\nSBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo)\nin a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010\ntruncate to 16. KVM then allocates one entry but loops over the original\nnum_events, causing out-of-bounds reads and writes. A nested guest\ntriggered:\n\nBUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\nRead of size 4 at addr ff600000074d46b0 by task init/1\nCall Trace:\n[] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\n[] kvm_sbi_ext_pmu_handler+0xca/0x268\n[] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\n[] kvm_riscv_vcpu_exit+0x48c/0x540\n[] kvm_arch_vcpu_ioctl_run+0x37e/0xc80\nAllocated by task 1:\n __kmalloc_noprof+0x19e/0x4b0\n kvm_riscv_vcpu_pmu_event_info+0x72/0x142\n kvm_sbi_ext_pmu_handler+0xca/0x268\n kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\n kvm_riscv_vcpu_exit+0x48c/0x540\n kvm_arch_vcpu_ioctl_run+0x37e/0xc80\nThe buggy address is located 0 bytes to the right of\n allocated 16-byte region [ff600000074d46a0, ff600000074d46b0)\n\nStore the shared-memory size in size_t and reject multiplication overflow.\nAllocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged\nto kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings.\nUse kvcalloc() to allow vmalloc fallback and an unsigned long loop index\nto match num_events." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The overflow is reached when a RISC-V KVM guest issues an SBI ECALL (EXC_SUPERVISOR_SYSCALL) for SBI_EXT_PMU_EVENT_GET_INFO, handled on the host KVM_RUN path via kvm_riscv_vcpu_exit, kvm_riscv_vcpu_sbi_ecall, kvm_sbi_ext_pmu_handler, and kvm_riscv_vcpu_pmu_event_info; this is a local guest hypercall path with no network or physical exposure.\nAC:L - A guest that sets flags=0, a 16-byte-aligned shared-memory GPA, and num_events=0x10000001 on RV64 makes num_events*sizeof(*einfo) truncate from 0x100000010 to 16, so kzalloc gets one entry while the loop uses the original count; the attacker controls every parameter and needs no race or uncontrollable host layout.\nPR:L - Issuing the SBI ECALL requires VS-mode in a KVM guest (tenant kernel or custom image) or a host kvm-group user running QEMU, not host init-namespace root; kvm_sbi_ext_pmu_handler has no capability check, and SBI PMU is enabled by default once kvm_riscv_vcpu_pmu_init succeeds.\nUI:N - The attacker guest issues SBI_EXT_PMU_EVENT_GET_INFO itself during KVM_RUN; no separate victim action such as attaching a device, mounting a filesystem, or confirming a prompt is required.\nS:C - The slab out-of-bounds access runs in the host kernel while handling a guest SBI call, crossing the KVM guest-to-hypervisor boundary so host heap corruption can compromise the hypervisor and co-located VMs, which CNA guidance rates Changed for KVM guest-to-host escape.\nC:H - After the truncated 16-byte allocation, the loop reads event_idx and event_data from adjacent host slab for 0x10000001 entries; that unbounded host-heap out-of-bounds read, together with the following heap corruption, can be leveraged for kernel memory disclosure.\nI:H - The same loop writes einfo[i].output (0 or 1) past the 16-byte object at a 16-byte stride for about 2^28 iterations, an unbounded host-slab out-of-bounds write that smashes neighboring objects and heap metadata and is scored High per CNA out-of-bounds-write guidance.\nA:H - KASAN reported a host slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info, and walking billions of bytes past a 16-byte allocation reliably oopses or panics the host kernel, denying service to the hypervisor and every co-located VM." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/riscv/kvm/vcpu_pmu.c" ], "versions": [ { "version": "e309fd113b9f6c34672a487be08fecb7e12e7e29", "lessThan": "ddbd71a3780942918a7d116d666313e5b3304d73", "status": "affected", "versionType": "git" }, { "version": "e309fd113b9f6c34672a487be08fecb7e12e7e29", "lessThan": "82088f88c96b99c27a974d09b02c2b133262fadf", "status": "affected", "versionType": "git" }, { "version": "e309fd113b9f6c34672a487be08fecb7e12e7e29", "lessThan": "735bc20c24187ca419c9d5e63860a54b91be34bd", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/riscv/kvm/vcpu_pmu.c" ], "versions": [ { "version": "6.18", "status": "affected" }, { "version": "0", "lessThan": "6.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "6.18.57" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ddbd71a3780942918a7d116d666313e5b3304d73" }, { "url": "https://git.kernel.org/stable/c/82088f88c96b99c27a974d09b02c2b133262fadf" }, { "url": "https://git.kernel.org/stable/c/735bc20c24187ca419c9d5e63860a54b91be34bd" } ], "title": "RISC-V: KVM: Fix PMU event info array size overflow", "x_generator": { "engine": "bippy-1.2.0" } } } }