cve-2021-47430
Vulnerability from cvelistv5
Published
2024-05-21 15:04
Modified
2024-12-19 07:41
Severity ?
Summary
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. ]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3958b9c34c2729597e182cc606cc43942fd19f7c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4e9ec1c65da98c293f75d83755dfa5e03075a6d0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f2447f6587b8ffe42ba04d14ce67d429a1163e5e
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/3958b9c34c2729597e182cc606cc43942fd19f7c
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/4e9ec1c65da98c293f75d83755dfa5e03075a6d0
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/f2447f6587b8ffe42ba04d14ce67d429a1163e5e
Impacted products
Vendor Product Version
Linux Linux Version: 3c73b81a9164d0c1b6379d6672d2772a9e95168e
Version: 3c73b81a9164d0c1b6379d6672d2772a9e95168e
Version: 3c73b81a9164d0c1b6379d6672d2772a9e95168e
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