CVE-2023-52504: x86/alternatives: Disable KASAN in apply_alternatives()

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-02 · updated 2026-06-17
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: x86/alternatives: Disable KASAN in apply_alternatives() Fei has reported that KASAN triggers during apply_alternatives() on a 5-level paging machine: BUG: KASAN: out-of-bounds in rcu_is_watching() Read of size 4 at addr ff110003ee6419a0 by task swapper/0/0 ... __asan_load4() rcu_is_watching() trace_hardirqs_on() text_poke_early() apply_alternatives() ... On machines with 5-level paging, cpu_feature_enabled(X86_FEATURE_LA57) gets patched. It includes KASAN code, where KASAN_SHADOW_START depends on __VIRTUAL_MASK_SHIFT, which is defined with cpu_feature_enabled(). KASAN gets confused when apply_alternatives() patches the KASAN_SHADOW_START users. A test patch that makes KASAN_SHADOW_START static, by replacing __VIRTUAL_MASK_SHIFT with 56, works around the issue. Fix it for real by disabling KASAN while the kernel is patching alternatives. [ mingo: updated the changelog ]

Affected products

Linux kernel: from 4.17 before 4.19.297; from 4.20 before 5.4.270; from 5.5 before 5.10.199; from 5.11 before 5.15.136; from 5.16 before 6.1.59; from 6.2 before 6.5.8 — fixed in 4.19.297, 5.10.199, 5.15.136, 5.4.270, 6.1.59, 6.5.8

How to fix

Upgrade to a fixed version: Linux kernel 4.19.297, 5.10.199, 5.15.136, 5.4.270. Check the vendor advisory for mitigations.

References

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