CVE-2023-52874

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux7a3a401874bea02f568aa416ac29170d8cde0dc2 < 2191950d35d8f81620ea8d4e04d983f664fe3a8aaffected
LinuxLinux7a3a401874bea02f568aa416ac29170d8cde0dc2 < de4c5bacca4f50233f1f791bec9eeb4dee1b14cdaffected
LinuxLinux7a3a401874bea02f568aa416ac29170d8cde0dc2 < 5d092b66119d774853cc9308522620299048a662affected
LinuxLinux6.4affected
LinuxLinux0 < 6.4unaffected
LinuxLinux6.5.12 <= 6.5.*unaffected
LinuxLinux6.6.2 <= 6.6.*unaffected
LinuxLinux6.7 <= *unaffected

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References