Bug 2532187 (CVE-2026-89513) - CVE-2026-89513 kernel: RISC-V: KVM: Fix PMU event info array size overflow
Summary: CVE-2026-89513 kernel: RISC-V: KVM: Fix PMU event info array size overflow
Keywords:
Status: NEW
Alias: CVE-2026-89513
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-11 21:12 UTC by OSIDB Bzimport
Modified: 2026-09-18 12:43 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2026-09-11 21:12:32 UTC
In the Linux kernel, the following vulnerability has been resolved:

RISC-V: KVM: Fix PMU event info array size overflow

SBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo)
in a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010
truncate to 16. KVM then allocates one entry but loops over the original
num_events, causing out-of-bounds reads and writes. A nested guest
triggered:

BUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142
Read of size 4 at addr ff600000074d46b0 by task init/1
Call Trace:
[<ffffffff8006471c>] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142
[<ffffffff800690c0>] kvm_sbi_ext_pmu_handler+0xca/0x268
[<ffffffff8006779e>] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6
[<ffffffff8006008c>] kvm_riscv_vcpu_exit+0x48c/0x540
[<ffffffff8005ea0a>] kvm_arch_vcpu_ioctl_run+0x37e/0xc80
Allocated by task 1:
 __kmalloc_noprof+0x19e/0x4b0
 kvm_riscv_vcpu_pmu_event_info+0x72/0x142
 kvm_sbi_ext_pmu_handler+0xca/0x268
 kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6
 kvm_riscv_vcpu_exit+0x48c/0x540
 kvm_arch_vcpu_ioctl_run+0x37e/0xc80
The buggy address is located 0 bytes to the right of
 allocated 16-byte region [ff600000074d46a0, ff600000074d46b0)

Store the shared-memory size in size_t and reject multiplication overflow.
Allocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged
to kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings.
Use kvcalloc() to allow vmalloc fallback and an unsigned long loop index
to match num_events.


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