In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer Both Intel and AMD consider it to be architecturally valid for XRSTOR to fail with #PF but nonetheless change the register state. The actual conditions under which this might occur are unclear [1], but it seems plausible that this might be triggered if one sibling thread unmaps a page and invalidates the shared TLB while another sibling thread is executing XRSTOR on the page in question. __fpu__restore_sig() can execute XRSTOR while the hardware registers are preserved on behalf of a different victim task (using the fpu_fpregs_owner_ctx mechanism), and, in theory, XRSTOR could fail but modify the registers. If this happens, then there is a window in which __fpu__restore_sig() could schedule out and the victim task could schedule back in without reloading its own FPU registers. This would result in part of the FPU state that __fpu__restore_sig() was attempting to load leaking into the victim task's user-visible state. Invalidate preserved FPU registers on XRSTOR failure to prevent this situation from corrupting any state. [1] Frequent readers of the errata lists might imagine "complex microarchitectural conditions".
History

Mon, 04 Nov 2024 12:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-05-21T14:19:30.864Z

Updated: 2024-11-04T12:01:51.053Z

Reserved: 2024-04-10T18:59:19.529Z

Link: CVE-2021-47226

cve-icon Vulnrichment

Updated: 2024-08-04T05:32:07.454Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-05-21T15:15:11.823

Modified: 2024-05-21T16:54:26.047

Link: CVE-2021-47226

cve-icon Redhat

Severity : Low

Publid Date: 2024-05-21T00:00:00Z

Links: CVE-2021-47226 - Bugzilla