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LOW · 3.3

CVE-2021-47430

In the Linux kernel, the following vulnerability has been resolved: x86/entry: Clear X86_FEATURE_SMAP when CONFIG_X86_SMAP=n Commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry...

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: x86/entry: Clear X86_FEATURE_SMAP when CONFIG_X86_SMAP=n Commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") added a warning if AC is set when in the kernel. Commit 662a0221893a3d ("x86/entry: Fix AC assertion") changed the warning to only fire if the CPU supports SMAP. However, the warning can still trigger on a machine that supports SMAP but where it's disabled in the kernel config and when running the syscall_nt selftest, for example: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 49 at irqentry_enter_from_user_mode CPU: 0 PID: 49 Comm: init Tainted: G T 5.15.0-rc4+ #98 e6202628ee053b4f310759978284bd8bb0ce6905 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 RIP: 0010:irqentry_enter_from_user_mode ... Call Trace: ? irqentry_enter ? exc_general_protection ? asm_exc_general_protection ? asm_exc_general_protectio IS_ENABLED(CONFIG_X86_SMAP) could be added to the warning condition, but even this would not be enough in case SMAP is disabled at boot time with the "nosmap" parameter. To be consistent with "nosmap" behaviour, clear X86_FEATURE_SMAP when !CONFIG_X86_SMAP. Found using entry-fuzz + satrandconfig. [ bp: Massage commit message. ]

CVSS Score

3.3

LOW

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW

Affected Products

VendorProductVersions
LinuxLinux Kernel>= 5.8.1, < 5.10.73

References

FAQ

What is CVE-2021-47430?

CVE-2021-47430 is a vulnerability with a CVSS score of 3.3 (LOW). In the Linux kernel, the following vulnerability has been resolved: x86/entry: Clear X86_FEATURE_SMAP when CONFIG_X86_SMAP=n Commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry...

How severe is CVE-2021-47430?

CVE-2021-47430 has been rated LOW with a CVSS base score of 3.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2021-47430?

Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel.