CVE-2024-39476

2024-07-0507:15:10

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

vulnerability

fix

raid5d

deadlock

hang

implementation

fix

md_check_recovery

reconfig_mutex

6.5 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.2%

JSON

In the Linux kernel, the following vulnerability has been resolved:

md/raid5: fix deadlock that raid5d() wait for itself to clear MD_SB_CHANGE_PENDING

Xiao reported that lvm2 test lvconvert-raid-takeover.sh can hang with
small possibility, the root cause is exactly the same as commit
bed9e27baf52 (“Revert “md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d””)

However, Dan reported another hang after that, and junxiao investigated
the problem and found out that this is caused by plugged bio can’t issue
from raid5d().

Current implementation in raid5d() has a weird dependence:

md_check_recovery() from raid5d() must hold ‘reconfig_mutex’ to clear
MD_SB_CHANGE_PENDING;
raid5d() handles IO in a deadloop, until all IO are issued;
IO from raid5d() must wait for MD_SB_CHANGE_PENDING to be cleared;

This behaviour is introduce before v2.6, and for consequence, if other
context hold ‘reconfig_mutex’, and md_check_recovery() can’t update
super_block, then raid5d() will waste one cpu 100% by the deadloop, until
‘reconfig_mutex’ is released.

Refer to the implementation from raid1 and raid10, fix this problem by
skipping issue IO if MD_SB_CHANGE_PENDING is still set after
md_check_recovery(), daemon thread will be woken up when ‘reconfig_mutex’
is released. Meanwhile, the hang problem will be fixed as well.

Affected configurations

Vulners

Node

linuxlinux_kernelRange6.1–4.19.316

linuxlinux_kernelRange4.20.0–5.4.278

linuxlinux_kernelRange5.5.0–5.10.219

linuxlinux_kernelRange5.11.0–5.15.161

linuxlinux_kernelRange5.16.0–6.1.94

linuxlinux_kernelRange6.2.0–6.6.34

linuxlinux_kernelRange6.7.0–6.9.5

linuxlinux_kernelRange6.10.0–6.10-rc1

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/md/raid5.c"
    ],
    "versions": [
      {
        "version": "f3d55bd5b7b9",
        "lessThan": "b32aa95843ca",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1c00bb624cd0",
        "lessThan": "634ba3c97ec4",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "782b3e71c957",
        "lessThan": "aa64464c8f4d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9e86dffd0b02",
        "lessThan": "098d54934814",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "5e2cf333b7bd",
        "lessThan": "3f8d5e802d4c",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "5e2cf333b7bd",
        "lessThan": "cd2538e5af49",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "5e2cf333b7bd",
        "lessThan": "e332a12f65d8",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "5e2cf333b7bd",
        "lessThan": "151f66bb618d",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/md/raid5.c"
    ],
    "versions": [
      {
        "version": "6.1",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.1",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.316",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.278",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.219",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.161",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.94",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.34",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.5",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10-rc1",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]