Description

In the Linux kernel, the following vulnerability has been resolved: RISC-V: KVM: Don't zero-out PMU snapshot area before freeing data With the latest Linux-6.11-rc3, the below NULL pointer crash is observed when SBI PMU snapshot is enabled for the guest and the guest is forcefully powered-off. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000508 Oops [#1] Modules linked in: kvm CPU: 0 UID: 0 PID: 61 Comm: term-poll Not tainted 6.11.0-rc3-00018-g44d7178dd77a #3 Hardware name: riscv-virtio,qemu (DT) epc : __kvm_write_guest_page+0x94/0xa6 [kvm] ra : __kvm_write_guest_page+0x54/0xa6 [kvm] epc : ffffffff01590e98 ra : ffffffff01590e58 sp : ffff8f80001f39b0 gp : ffffffff81512a60 tp : ffffaf80024872c0 t0 : ffffaf800247e000 t1 : 00000000000007e0 t2 : 0000000000000000 s0 : ffff8f80001f39f0 s1 : 00007fff89ac4000 a0 : ffffffff015dd7e8 a1 : 0000000000000086 a2 : 0000000000000000 a3 : ffffaf8000000000 a4 : ffffaf80024882c0 a5 : 0000000000000000 a6 : ffffaf800328d780 a7 : 00000000000001cc s2 : ffffaf800197bd00 s3 : 00000000000828c4 s4 : ffffaf800248c000 s5 : ffffaf800247d000 s6 : 0000000000001000 s7 : 0000000000001000 s8 : 0000000000000000 s9 : 00007fff861fd500 s10: 0000000000000001 s11: 0000000000800000 t3 : 00000000000004d3 t4 : 00000000000004d3 t5 : ffffffff814126e0 t6 : ffffffff81412700 status: 0000000200000120 badaddr: 0000000000000508 cause: 000000000000000d [<ffffffff01590e98>] __kvm_write_guest_page+0x94/0xa6 [kvm] [<ffffffff015943a6>] kvm_vcpu_write_guest+0x56/0x90 [kvm] [<ffffffff015a175c>] kvm_pmu_clear_snapshot_area+0x42/0x7e [kvm] [<ffffffff015a1972>] kvm_riscv_vcpu_pmu_deinit.part.0+0xe0/0x14e [kvm] [<ffffffff015a2ad0>] kvm_riscv_vcpu_pmu_deinit+0x1a/0x24 [kvm] [<ffffffff0159b344>] kvm_arch_vcpu_destroy+0x28/0x4c [kvm] [<ffffffff0158e420>] kvm_destroy_vcpus+0x5a/0xda [kvm] [<ffffffff0159930c>] kvm_arch_destroy_vm+0x14/0x28 [kvm] [<ffffffff01593260>] kvm_destroy_vm+0x168/0x2a0 [kvm] [<ffffffff015933d4>] kvm_put_kvm+0x3c/0x58 [kvm] [<ffffffff01593412>] kvm_vm_release+0x22/0x2e [kvm] Clearly, the kvm_vcpu_write_guest() function is crashing because it is being called from kvm_pmu_clear_snapshot_area() upon guest tear down. To address the above issue, simplify the kvm_pmu_clear_snapshot_area() to not zero-out PMU snapshot area from kvm_pmu_clear_snapshot_area() because the guest is anyway being tore down. The kvm_pmu_clear_snapshot_area() is also called when guest changes PMU snapshot area of a VCPU but even in this case the previous PMU snaphsot area must not be zeroed-out because the guest might have reclaimed the pervious PMU snapshot area for some other purpose.

Metrics

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

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CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

NIST: NVD

Base Score:  5.5 MEDIUM

Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS 2.0 Severity and Vector Strings:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://git.kernel.org/stable/c/47d40d93292d9cff8dabb735bed83d930fa03950	Patch
https://git.kernel.org/stable/c/6d0a5dcfc78bd18f2abb9641f83380135494559b	Patch
https://git.kernel.org/stable/c/81aa95fd5bd14ff49617f07fa79a8d1f1cf2ce9a	Patch

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-476	NULL Pointer Dereference	NIST

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Change History

2 change records found show changes

Initial Analysis by NIST 10/24/2024 10:32:20 AM

Action	Type	Old Value	New Value
Added	CVSS V3.1		NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Added	CWE		NIST CWE-476
Added	CPE Configuration		OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.10 up to (excluding) 6.10.13 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.11 up to (excluding) 6.11.2
Changed	Reference Type	https://git.kernel.org/stable/c/47d40d93292d9cff8dabb735bed83d930fa03950 No Types Assigned	https://git.kernel.org/stable/c/47d40d93292d9cff8dabb735bed83d930fa03950 Patch
Changed	Reference Type	https://git.kernel.org/stable/c/6d0a5dcfc78bd18f2abb9641f83380135494559b No Types Assigned	https://git.kernel.org/stable/c/6d0a5dcfc78bd18f2abb9641f83380135494559b Patch
Changed	Reference Type	https://git.kernel.org/stable/c/81aa95fd5bd14ff49617f07fa79a8d1f1cf2ce9a No Types Assigned	https://git.kernel.org/stable/c/81aa95fd5bd14ff49617f07fa79a8d1f1cf2ce9a Patch

New CVE Received from kernel.org 10/21/2024 8:15:08 AM

Action	Type	Old Value	New Value
Added	Description		Record truncated, showing 500 of 2715 characters. View Entire Change Record In the Linux kernel, the following vulnerability has been resolved: RISC-V: KVM: Don't zero-out PMU snapshot area before freeing data With the latest Linux-6.11-rc3, the below NULL pointer crash is observed when SBI PMU snapshot is enabled for the guest and the guest is forcefully powered-off. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000508 Oops [#1] Modules linked in: kvm CPU: 0 UID: 0 PID: 61 Comm: term-poll Not tainted 6.11.0-rc3-00018-g44d7178d
Added	Reference		kernel.org https://git.kernel.org/stable/c/47d40d93292d9cff8dabb735bed83d930fa03950 [No types assigned]
Added	Reference		kernel.org https://git.kernel.org/stable/c/6d0a5dcfc78bd18f2abb9641f83380135494559b [No types assigned]
Added	Reference		kernel.org https://git.kernel.org/stable/c/81aa95fd5bd14ff49617f07fa79a8d1f1cf2ce9a [No types assigned]