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

2024-03-0221:52:18

Linux

www.cve.org

linux kernel

vulnerability

x86

kasan

apply_alternatives

5-level paging

cpu_feature_enabled

patch

alternatives

7.5 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

10.5%

JSON

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 ]

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/kernel/alternative.c"
    ],
    "versions": [
      {
        "version": "6657fca06e3f",
        "lessThan": "3719d3c36aa8",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "3770c38cd6a6",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "6788b10620ca",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "ecba5afe86f3",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "5b784489c815",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "cd287cc208df",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "6657fca06e3f",
        "lessThan": "d35652a5fc99",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/kernel/alternative.c"
    ],
    "versions": [
      {
        "version": "4.17",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "4.17",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.297",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.270",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.199",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.136",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.59",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.5.8",
        "lessThanOrEqual": "6.5.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]