UBUNTU-CVE-2023-52504

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UBUNTU-CVE-2023-52504

Summary:

Details: 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 ]

References: https://ubuntu.com/security/CVE-2023-52504, https://git.kernel.org/linus/d35652a5fc9944784f6f50a5c979518ff8dacf61, https://www.cve.org/CVERecord?id=CVE-2023-52504, https://ubuntu.com/security/notices/USN-6831-1, https://ubuntu.com/security/notices/USN-6867-1