ghsa-82mj-rf9f-84h3
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Prevent access to vCPU events before init
Another day, another syzkaller bug. KVM erroneously allows userspace to pend vCPU events for a vCPU that hasn't been initialized yet, leading to KVM interpreting a bunch of uninitialized garbage for routing / injecting the exception.
In one case the injection code and the hyp disagree on whether the vCPU has a 32bit EL1 and put the vCPU into an illegal mode for AArch64, tripping the BUG() in exception_target_el() during the next injection:
kernel BUG at arch/arm64/kvm/inject_fault.c:40! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 3 UID: 0 PID: 318 Comm: repro Not tainted 6.17.0-rc4-00104-g10fd0285305d #6 PREEMPT Hardware name: linux,dummy-virt (DT) pstate: 21402009 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : exception_target_el+0x88/0x8c lr : pend_serror_exception+0x18/0x13c sp : ffff800082f03a10 x29: ffff800082f03a10 x28: ffff0000cb132280 x27: 0000000000000000 x26: 0000000000000000 x25: ffff0000c2a99c20 x24: 0000000000000000 x23: 0000000000008000 x22: 0000000000000002 x21: 0000000000000004 x20: 0000000000008000 x19: ffff0000c2a99c20 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200000c0 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff800082f03af8 x7 : 0000000000000000 x6 : 0000000000000000 x5 : ffff800080f621f0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 000000000040009b x1 : 0000000000000003 x0 : ffff0000c2a99c20 Call trace: exception_target_el+0x88/0x8c (P) kvm_inject_serror_esr+0x40/0x3b4 __kvm_arm_vcpu_set_events+0xf0/0x100 kvm_arch_vcpu_ioctl+0x180/0x9d4 kvm_vcpu_ioctl+0x60c/0x9f4 __arm64_sys_ioctl+0xac/0x104 invoke_syscall+0x48/0x110 el0_svc_common.constprop.0+0x40/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x34/0xf0 el0t_64_sync_handler+0xa0/0xe4 el0t_64_sync+0x198/0x19c Code: f946bc01 b4fffe61 9101e020 17fffff2 (d4210000)
Reject the ioctls outright as no sane VMM would call these before KVM_ARM_VCPU_INIT anyway. Even if it did the exception would've been thrown away by the eventual reset of the vCPU's state.
{
"affected": [],
"aliases": [
"CVE-2025-40102"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-30T10:15:34Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Prevent access to vCPU events before init\n\nAnother day, another syzkaller bug. KVM erroneously allows userspace to\npend vCPU events for a vCPU that hasn\u0027t been initialized yet, leading to\nKVM interpreting a bunch of uninitialized garbage for routing /\ninjecting the exception.\n\nIn one case the injection code and the hyp disagree on whether the vCPU\nhas a 32bit EL1 and put the vCPU into an illegal mode for AArch64,\ntripping the BUG() in exception_target_el() during the next injection:\n\n kernel BUG at arch/arm64/kvm/inject_fault.c:40!\n Internal error: Oops - BUG: 00000000f2000800 [#1] SMP\n CPU: 3 UID: 0 PID: 318 Comm: repro Not tainted 6.17.0-rc4-00104-g10fd0285305d #6 PREEMPT\n Hardware name: linux,dummy-virt (DT)\n pstate: 21402009 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n pc : exception_target_el+0x88/0x8c\n lr : pend_serror_exception+0x18/0x13c\n sp : ffff800082f03a10\n x29: ffff800082f03a10 x28: ffff0000cb132280 x27: 0000000000000000\n x26: 0000000000000000 x25: ffff0000c2a99c20 x24: 0000000000000000\n x23: 0000000000008000 x22: 0000000000000002 x21: 0000000000000004\n x20: 0000000000008000 x19: ffff0000c2a99c20 x18: 0000000000000000\n x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200000c0\n x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000\n x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000\n x8 : ffff800082f03af8 x7 : 0000000000000000 x6 : 0000000000000000\n x5 : ffff800080f621f0 x4 : 0000000000000000 x3 : 0000000000000000\n x2 : 000000000040009b x1 : 0000000000000003 x0 : ffff0000c2a99c20\n Call trace:\n exception_target_el+0x88/0x8c (P)\n kvm_inject_serror_esr+0x40/0x3b4\n __kvm_arm_vcpu_set_events+0xf0/0x100\n kvm_arch_vcpu_ioctl+0x180/0x9d4\n kvm_vcpu_ioctl+0x60c/0x9f4\n __arm64_sys_ioctl+0xac/0x104\n invoke_syscall+0x48/0x110\n el0_svc_common.constprop.0+0x40/0xe0\n do_el0_svc+0x1c/0x28\n el0_svc+0x34/0xf0\n el0t_64_sync_handler+0xa0/0xe4\n el0t_64_sync+0x198/0x19c\n Code: f946bc01 b4fffe61 9101e020 17fffff2 (d4210000)\n\nReject the ioctls outright as no sane VMM would call these before\nKVM_ARM_VCPU_INIT anyway. Even if it did the exception would\u0027ve been\nthrown away by the eventual reset of the vCPU\u0027s state.",
"id": "GHSA-82mj-rf9f-84h3",
"modified": "2025-10-30T12:31:10Z",
"published": "2025-10-30T12:31:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40102"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0aa1b76fe1429629215a7c79820e4b96233ac4a3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/64a04e6320fc5affbadc59dc7024d79f909bfe84"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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