{"id":"CVE-2021-47226","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer\n\nBoth Intel and AMD consider it to be architecturally valid for XRSTOR to\nfail with #PF but nonetheless change the register state.  The actual\nconditions under which this might occur are unclear [1], but it seems\nplausible that this might be triggered if one sibling thread unmaps a page\nand invalidates the shared TLB while another sibling thread is executing\nXRSTOR on the page in question.\n\n__fpu__restore_sig() can execute XRSTOR while the hardware registers\nare preserved on behalf of a different victim task (using the\nfpu_fpregs_owner_ctx mechanism), and, in theory, XRSTOR could fail but\nmodify the registers.\n\nIf this happens, then there is a window in which __fpu__restore_sig()\ncould schedule out and the victim task could schedule back in without\nreloading its own FPU registers. This would result in part of the FPU\nstate that __fpu__restore_sig() was attempting to load leaking into the\nvictim task's user-visible state.\n\nInvalidate preserved FPU registers on XRSTOR failure to prevent this\nsituation from corrupting any state.\n\n[1] Frequent readers of the errata lists might imagine \"complex\n    microarchitectural conditions\".","modified":"2026-03-13T05:16:31.164604Z","published":"2024-05-21T15:15:11.823Z","references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817"},{"type":"FIX","url":"https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a"},{"type":"FIX","url":"https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14"}],"affected":[{"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-47226.json","unresolved_ranges":[{"events":[{"introduced":"5.2"},{"fixed":"5.10.46"}]},{"events":[{"introduced":"5.11"},{"fixed":"5.12.13"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc1"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc2"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc3"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc4"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc5"}]},{"events":[{"introduced":"0"},{"last_affected":"5.13-rc6"}]}]}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"}]}