# CVE-2023-52504: linux: In the Linux kernel, the following vulnerability has been resolved:  x86/alternatives: Disable KASAN in apply_alterna...

CVE-2023-52504 is fixed in linux on 1 platform, first by DEBIAN-CVE-2023-52504, released March 2, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2023-52504
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0028
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 2, 2024

## 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 ]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.64-1 | [DEBIAN-CVE-2023-52504](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52504.md) | Mar 2, 2024 |
| Linux | linux Debian 13.5 (trixie) | 6.5.8-1 | [DEBIAN-CVE-2023-52504](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52504.md) | Mar 2, 2024 |
| Linux | linux Debian 14 | 6.5.8-1 | [DEBIAN-CVE-2023-52504](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52504.md) | Mar 2, 2024 |

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