Out-of-bounds Read Affecting kernel-default-livepatch package, versions <5.14.21-150500.55.59.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (12th percentile)

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  • Snyk IDSNYK-SLES155-KERNELDEFAULTLIVEPATCH-6746905
  • published1 May 2024
  • disclosed30 Apr 2024

Introduced: 30 Apr 2024

CVE-2023-52504  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade SLES:15.5 kernel-default-livepatch to version 5.14.21-150500.55.59.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default-livepatch package and not the kernel-default-livepatch package as distributed by SLES. See How to fix? for SLES:15.5 relevant fixed versions and status.

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 ]

CVSS Scores

version 3.1