CVE - CVE-2021-47226

CVE-ID
CVE-2021-47226	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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".
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14 URL:https://git.kernel.org/stable/c/002665dcba4bbec8c82f0aeb4bd3f44334ed2c14 MISC:https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817 URL:https://git.kernel.org/stable/c/a7748e021b9fb7739e3cb88449296539de0b6817 MISC:https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a URL:https://git.kernel.org/stable/c/d8778e393afa421f1f117471144f8ce6deb6953a
Assigning CNA
kernel.org
Date Record Created
20240410	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240410)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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