Fiche vulnérabilité
CVE-2021-47226 : faille élevée linux linux kernel (CVSS 7.1)
Description
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".
En bref
- Sévérité
- Élevée (CVSS 7.1)
- Vecteur CVSS
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- Exploitation active
- Non signalée par la CISA
- Publication
- 21 mai 2024
- Dernière mise à jour
- 4 août 2026
Produits concernés
- linux linux kernel