Linux Kernel up to 4.19.217/5.4.161/5.10.81/5.15.4 hyperv set_hv_tscchange_cb null pointer dereference

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 4.19.217/5.4.161/5.10.81/5.15.4. The affected element is the function set_hv_tscchange_cb of the component hyperv. The manipulation results in null pointer dereference. This vulnerability is known as CVE-2021-47217. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 4.19.217/5.4.161/5.10.81/5.15.4. Affected is the function set_hv_tscchange_cb of the component hyperv. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails Check for a valid hv_vp_index array prior to derefencing hv_vp_index when setting Hyper-V's TSC change callback. If Hyper-V setup failed in hyperv_init(), the kernel will still report that it's running under Hyper-V, but will have silently disabled nearly all functionality. BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:set_hv_tscchange_cb+0x15/0xa0 Code: 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08 ... Call Trace: kvm_arch_init+0x17c/0x280 kvm_init+0x31/0x330 vmx_init+0xba/0x13a do_one_initcall+0x41/0x1c0 kernel_init_freeable+0x1f2/0x23b kernel_init+0x16/0x120 ret_from_fork+0x22/0x30

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2021-47217. The exploitability is told to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 4.19.218, 5.4.162, 5.10.82, 5.15.5 or 5.16 eliminates this vulnerability. Applying the patch b20ec58f8a6f/b0e44dfb4e4c/9c177eee116c/8823ea27fff6/daf972118c51 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.19.217
• 5.4.161
• 5.10.0
• 5.10.1
• 5.10.2
• 5.10.3
• 5.10.4
• 5.10.5
• 5.10.6
• 5.10.7
• 5.10.8
• 5.10.9
• 5.10.10
• 5.10.11
• 5.10.12
• 5.10.13
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• 5.10.15
• 5.10.16
• 5.10.17
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• 5.10.21
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• 5.10.30
• 5.10.31
• 5.10.32
• 5.10.33
• 5.10.34
• 5.10.35
• 5.10.36
• 5.10.37
• 5.10.38
• 5.10.39
• 5.10.40
• 5.10.41
• 5.10.42
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• 5.10.46
• 5.10.47
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• 5.10.57
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• 5.10.60
• 5.10.61
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• 5.10.65
• 5.10.66
• 5.10.67
• 5.10.68
• 5.10.69
• 5.10.70
• 5.10.71
• 5.10.72
• 5.10.73
• 5.10.74
• 5.10.75
• 5.10.76
• 5.10.77
• 5.10.78
• 5.10.79
• 5.10.80
• 5.10.81
• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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