Linux Kernel up to 6.5.11/6.6.1 __tdx_hypercall privilege escalation

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 6.5.11/6.6.1. This affects the function __tdx_hypercall. This manipulation causes an unknown weakness. This vulnerability appears as CVE-2023-52874. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.5.11/6.6.1 and classified as problematic. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the untrusted VMM, the registers that the TDX guest shares to the VMM need to be cleared to avoid speculative execution of VMM-provided values. RSI is specified in the bitmap of those registers, but it is missing when zeroing out those registers in the current TDX_HYPERCALL. It was there when it was originally added in commit 752d13305c78 ("x86/tdx: Expand __tdx_hypercall() to handle more arguments"), but was later removed in commit 1e70c680375a ("x86/tdx: Do not corrupt frame-pointer in __tdx_hypercall()"), which was correct because %rsi is later restored in the "pop %rsi". However a later commit 7a3a401874be ("x86/tdx: Drop flags from __tdx_hypercall()") removed that "pop %rsi" but forgot to add the "xor %rsi, %rsi" back. Fix by adding it back.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2023-52874 since 05/21/2024. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.5.12 or 6.6.2 eliminates this vulnerability. Applying the patch 2191950d35d8/de4c5bacca4f/5d092b66119d 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

• 6.5.0
• 6.5.1
• 6.5.2
• 6.5.3
• 6.5.4
• 6.5.5
• 6.5.6
• 6.5.7
• 6.5.8
• 6.5.9
• 6.5.10
• 6.5.11
• 6.6.0
• 6.6.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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