CVE-2021-47226
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2021-47226
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47226.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2021-47226
- Related
- Published
- 2024-05-21T15:15:11Z
- Modified
- 2024-11-21T06:35:39Z
- Summary
- [none]
- Details
-
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.
fpurestoresig() can execute XRSTOR while the hardware registers are preserved on behalf of a different victim task (using the fpufpregsownerctx mechanism), and, in theory, XRSTOR could fail but modify the registers.
If this happens, then there is a window in which fpurestoresig() 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 fpurestoresig() 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".
- References
Affected packages
Debian:11 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:12 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source
Debian:13 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source