CVE-2024-35801

Summary

In the Linux kernel, the following vulnerability has been resolved:

x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD

Commit 672365477ae8 ("x86/fpu: Update XFD state where required") and commit 8bf26758ca96 ("x86/fpu: Add XFD state to fpstate") introduced a per CPU variable xfd_state to keep the MSR_IA32_XFD value cached, in order to avoid unnecessary writes to the MSR.

On CPU hotplug MSR_IA32_XFD is reset to the init_fpstate.xfd, which wipes out any stale state. But the per CPU cached xfd value is not reset, which brings them out of sync.

As a consequence a subsequent xfd_update_state() might fail to update the MSR which in turn can result in XRSTOR raising a #NM in kernel space, which crashes the kernel.

To fix this, introduce xfd_set_state() to write xfd_state together with MSR_IA32_XFD, and use it in all places that set MSR_IA32_XFD.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux672365477ae8afca5a1cca98c1deb733235e4525 < 21c7c00dae55cb0e3810d5f9506b58f68475d41daffected
LinuxLinux672365477ae8afca5a1cca98c1deb733235e4525 < 1acbca933313aa866e39996904c9aca4d435c4cdaffected
LinuxLinux672365477ae8afca5a1cca98c1deb733235e4525 < 92b0f04e937665bde5768f3fcc622dcce44413d8affected
LinuxLinux672365477ae8afca5a1cca98c1deb733235e4525 < b61e3b7055ac6edee4be071c52f48c26472d2624affected
LinuxLinux672365477ae8afca5a1cca98c1deb733235e4525 < 10e4b5166df9ff7a2d5316138ca668b42d004422affected
LinuxLinux5.16affected
LinuxLinux0 < 5.16unaffected
LinuxLinux6.1.84 <= 6.1.*unaffected
LinuxLinux6.6.24 <= 6.6.*unaffected
LinuxLinux6.7.12 <= 6.7.*unaffected
LinuxLinux6.8.3 <= 6.8.*unaffected
LinuxLinux6.9 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

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

CVE Program Container

Additional References

References