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PUBLISHED

CVE-2024-35801

x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD

Reserved:2024-05-17
Published:2024-05-17
Updated:2024-06-06

Description

In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD Commit 672365477ae8 ("x86/fpu: Update XFD state where required") and commit 8bf26758ca96 ("x86/fpu: Add XFD state to fpstate") introduced a per CPU variable xfd_state to keep the MSR_IA32_XFD value cached, in order to avoid unnecessary writes to the MSR. On CPU hotplug MSR_IA32_XFD is reset to the init_fpstate.xfd, which wipes out any stale state. But the per CPU cached xfd value is not reset, which brings them out of sync. As a consequence a subsequent xfd_update_state() might fail to update the MSR which in turn can result in XRSTOR raising a #NM in kernel space, which crashes the kernel. To fix this, introduce xfd_set_state() to write xfd_state together with MSR_IA32_XFD, and use it in all places that set MSR_IA32_XFD.

Product status

Default status
unaffected

672365477ae8 before 21c7c00dae55
affected

672365477ae8 before 1acbca933313
affected

672365477ae8 before 92b0f04e9376
affected

672365477ae8 before b61e3b7055ac
affected

672365477ae8 before 10e4b5166df9
affected

Default status
affected

5.16
affected

Any version before 5.16
unaffected

6.1.84
unaffected

6.6.24
unaffected

6.7.12
unaffected

6.8.3
unaffected

6.9
unaffected

References

https://git.kernel.org/stable/c/21c7c00dae55cb0e3810d5f9506b58f68475d41d

https://git.kernel.org/stable/c/1acbca933313aa866e39996904c9aca4d435c4cd

https://git.kernel.org/stable/c/92b0f04e937665bde5768f3fcc622dcce44413d8

https://git.kernel.org/stable/c/b61e3b7055ac6edee4be071c52f48c26472d2624

https://git.kernel.org/stable/c/10e4b5166df9ff7a2d5316138ca668b42d004422

cve.org CVE-2024-35801

nvd.nist.gov CVE-2024-35801

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