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".
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Affected Vendors & Products
References
History
Tue, 29 Apr 2025 19:45:00 +0000
Type | Values Removed | Values Added |
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First Time appeared |
Linux
Linux linux Kernel |
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Weaknesses | CWE-203 | |
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.13:rc6:*:*:*:*:*:* |
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Vendors & Products |
Linux
Linux linux Kernel |
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Metrics |
cvssV3_1
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cvssV3_1
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Mon, 04 Nov 2024 12:15:00 +0000
Type | Values Removed | Values Added |
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Metrics |
ssvc
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Status: PUBLISHED
Assigner: Linux
Published: 2024-05-21T14:19:30.864Z
Updated: 2024-12-19T07:37:46.265Z
Reserved: 2024-04-10T18:59:19.529Z
Link: CVE-2021-47226

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

Status : Analyzed
Published: 2024-05-21T15:15:11.823
Modified: 2025-04-29T19:26:36.690
Link: CVE-2021-47226
