UBUNTU-CVE-2024-40953
In the Linux kernel, the following vulnerability has been resolved: KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() Use {READ,WRITE}_ONCE() to access kvm->last_boosted_vcpu to ensure the loads and stores are atomic. In the extremely unlikely scenario the compiler tears the stores, it's theoretically possible for KVM to attempt to get a vCPU using an out-of-bounds index, e.g. if the write is split into multiple 8-bit stores, and is paired with a 32-bit load on a VM with 257 vCPUs: CPU0 CPU1 last_boosted_vcpu = 0xff; (last_boosted_vcpu = 0x100) last_boosted_vcpu[15:8] = 0x01; i = (last_boosted_vcpu = 0x1ff) last_boosted_vcpu[7:0] = 0x00; vcpu = kvm->vcpu_array[0x1ff]; As detected by KCSAN: BUG: KCSAN: data-race in kvm_vcpu_on_spin [kvm] / kvm_vcpu_on_spin [kvm] write to 0xffffc90025a92344 of 4 bytes by task 4340 on cpu 16: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4112) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) read to 0xffffc90025a92344 of 4 bytes by task 4342 on cpu 4: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4069) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) value changed: 0x00000012 -> 0x00000000
02 / AFFECTED SOFTWARE
Affected packages
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
19 explicit affected versions
6 explicit affected versions
67 explicit affected versions
10 explicit affected versions
52 explicit affected versions
72 explicit affected versions
60 explicit affected versions
53 explicit affected versions
10 explicit affected versions
3 explicit affected versions
9 explicit affected versions
59 explicit affected versions
191 explicit affected versions
7 explicit affected versions
58 explicit affected versions
4 explicit affected versions
99 explicit affected versions
13 explicit affected versions
85 explicit affected versions
6 explicit affected versions
35 explicit affected versions
19 explicit affected versions
19 explicit affected versions
18 explicit affected versions
18 explicit affected versions
118 explicit affected versions
41 explicit affected versions
9 explicit affected versions
101 explicit affected versions
13 explicit affected versions
4 explicit affected versions
121 explicit affected versions
23 explicit affected versions
13 explicit affected versions
1 explicit affected versions
21 explicit affected versions
16 explicit affected versions
10 explicit affected versions
56 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
111 explicit affected versions
50 explicit affected versions
12 explicit affected versions
14 explicit affected versions
7 explicit affected versions
88 explicit affected versions
12 explicit affected versions
104 explicit affected versions
112 explicit affected versions
12 explicit affected versions
4 explicit affected versions
99 explicit affected versions
120 explicit affected versions
15 explicit affected versions
5 explicit affected versions
10 explicit affected versions
37 explicit affected versions
13 explicit affected versions
2 explicit affected versions
10 explicit affected versions
34 explicit affected versions
1 explicit affected versions
37 explicit affected versions
26 explicit affected versions
13 explicit affected versions
144 explicit affected versions
12 explicit affected versions
1 explicit affected versions
29 explicit affected versions
92 explicit affected versions
13 explicit affected versions
64 explicit affected versions
3 explicit affected versions
4 explicit affected versions
1 explicit affected versions
87 explicit affected versions
59 explicit affected versions
104 explicit affected versions
22 explicit affected versions
33 explicit affected versions
23 explicit affected versions
10 explicit affected versions
1 explicit affected versions
188 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
102 explicit affected versions
138 explicit affected versions
2 explicit affected versions
50 explicit affected versions
44 explicit affected versions
132 explicit affected versions
60 explicit affected versions
165 explicit affected versions
154 explicit affected versions
10 explicit affected versions
26 explicit affected versions
11 explicit affected versions
37 explicit affected versions
1 explicit affected versions
3 explicit affected versions
12 explicit affected versions
13 explicit affected versions
11 explicit affected versions
139 explicit affected versions
62 explicit affected versions
16 explicit affected versions
63 explicit affected versions
12 explicit affected versions
51 explicit affected versions
116 explicit affected versions
3 explicit affected versions
93 explicit affected versions
1 explicit affected versions
2 explicit affected versions
69 explicit affected versions
51 explicit affected versions
92 explicit affected versions
9 explicit affected versions
12 explicit affected versions
47 explicit affected versions
27 explicit affected versions
34 explicit affected versions
1 explicit affected versions
1 explicit affected versions
98 explicit affected versions
5 explicit affected versions
8 explicit affected versions
24 explicit affected versions
5 explicit affected versions
8 explicit affected versions
1 explicit affected versions
10 explicit affected versions
8 explicit affected versions
13 explicit affected versions
91 explicit affected versions
13 explicit affected versions
55 explicit affected versions
7 explicit affected versions
140 explicit affected versions
94 explicit affected versions
52 explicit affected versions
10 explicit affected versions
12 explicit affected versions
15 explicit affected versions
91 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
37 explicit affected versions
12 explicit affected versions
14 explicit affected versions
38 explicit affected versions
167 explicit affected versions
52 explicit affected versions
9 explicit affected versions
51 explicit affected versions
11 explicit affected versions
4 explicit affected versions
60 explicit affected versions
7 explicit affected versions
33 explicit affected versions
97 explicit affected versions
63 explicit affected versions
121 explicit affected versions
4 explicit affected versions
1 explicit affected versions
1 explicit affected versions
58 explicit affected versions
13 explicit affected versions
43 explicit affected versions
57 explicit affected versions
10 explicit affected versions
8 explicit affected versions
7 explicit affected versions
14 explicit affected versions
92 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
69 explicit affected versions
5 explicit affected versions
11 explicit affected versions
41 explicit affected versions
57 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() Use {READ,WRITE}_ONCE() to access kvm->last_boosted_vcpu to ensure the loads and stores are atomic. In the extremely unlikely scenario the compiler tears the stores, it's theoretically possible for KVM to attempt to get a vCPU using an out-of-bounds index, e.g. if the write is split into multiple 8-bit stores, and is paired with a 32-bit load on a VM with 257 vCPUs: CPU0 CPU1 last_boosted_vcpu = 0xff; (last_boosted_vcpu = 0x100) last_boosted_vcpu[15:8] = 0x01; i = (last_boosted_vcpu = 0x1ff) last_boosted_vcpu[7:0] = 0x00; vcpu = kvm->vcpu_array[0x1ff]; As detected by KCSAN: BUG: KCSAN: data-race in kvm_vcpu_on_spin [kvm] / kvm_vcpu_on_spin [kvm] write to 0xffffc90025a92344 of 4 bytes by task 4340 on cpu 16: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4112) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) read to 0xffffc90025a92344 of 4 bytes by task 4342 on cpu 4: kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4069) kvm handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:? arch/x86/kvm/vmx/vmx.c:6606) kvm_intel vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890) __x64_sys_ioctl (fs/ioctl.c:890) x64_sys_call (arch/x86/entry/syscall_64.c:33) do_syscall_64 (arch/x86/entry/common.c:?) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) value changed: 0x00000012 -> 0x00000000
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/49f683b41f28918df3e51ddc0d928cb2e934ccdb
- https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb
- https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c
- https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60
- https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20
- https://ubuntu.com/security/CVE-2024-40953
- https://ubuntu.com/security/notices/USN-6999-1
- https://ubuntu.com/security/notices/USN-6999-2
- https://ubuntu.com/security/notices/USN-7004-1
- https://ubuntu.com/security/notices/USN-7005-1
- https://ubuntu.com/security/notices/USN-7005-2
- https://ubuntu.com/security/notices/USN-7008-1
- https://ubuntu.com/security/notices/USN-7029-1
- https://ubuntu.com/security/notices/USN-7288-1
- https://ubuntu.com/security/notices/USN-7288-2
- https://ubuntu.com/security/notices/USN-7289-1
- https://ubuntu.com/security/notices/USN-7289-2
- https://ubuntu.com/security/notices/USN-7289-3
- https://ubuntu.com/security/notices/USN-7289-4
- https://ubuntu.com/security/notices/USN-7291-1
- https://ubuntu.com/security/notices/USN-7293-1
- https://ubuntu.com/security/notices/USN-7294-1
- https://ubuntu.com/security/notices/USN-7294-2
- https://ubuntu.com/security/notices/USN-7294-3
- https://ubuntu.com/security/notices/USN-7294-4
- https://ubuntu.com/security/notices/USN-7295-1
- https://ubuntu.com/security/notices/USN-7305-1
- https://ubuntu.com/security/notices/USN-7308-1
- https://ubuntu.com/security/notices/USN-7331-1
- https://ubuntu.com/security/notices/USN-7388-1
- https://ubuntu.com/security/notices/USN-7389-1
- https://ubuntu.com/security/notices/USN-7390-1
- https://ubuntu.com/security/notices/USN-7393-1
- https://ubuntu.com/security/notices/USN-7401-1
- https://ubuntu.com/security/notices/USN-7413-1
- https://ubuntu.com/security/notices/USN-7458-1
- https://ubuntu.com/security/notices/USN-7539-1
- https://ubuntu.com/security/notices/USN-7540-1
- https://www.cve.org/CVERecord?id=CVE-2024-40953