# CVE-2021-47430: linux: In the Linux kernel, the following vulnerability has been resolved:  x86/entry: Clear X86_FEATURE_SMAP when CONFIG_X8...

CVE-2021-47430 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47430, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47430
- Priority: Routine
- CVSS: 3.3 (low)
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## 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. ]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.12-1 | [DEBIAN-CVE-2021-47430](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47430.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.12-1 | [DEBIAN-CVE-2021-47430](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47430.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.14.12-1 | [DEBIAN-CVE-2021-47430](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47430.md) | May 21, 2024 |

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