CVE-2024-26757

2024-04-0317:15:52

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

web.nvd.nist.gov

linux kernel

md_check_recovery

vulnerability

dm-raid

sync thread

read-only array

nvd

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

9.2%

JSON

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

md: Don’t ignore read-only array in md_check_recovery()

Usually if the array is not read-write, md_check_recovery() won’t
register new sync_thread in the first place. And if the array is
read-write and sync_thread is registered, md_set_readonly() will
unregister sync_thread before setting the array read-only. md/raid
follow this behavior hence there is no problem.

After commit f52f5c71f3d4 (“md: fix stopping sync thread”), following
hang can be triggered by test shell/integrity-caching.sh:

array is read-only. dm-raid update super block:
rs_update_sbs
ro = mddev->ro
mddev->ro = 0
-> set array read-write
md_update_sb
register new sync thread concurrently.
dm-raid set array back to read-only:
rs_update_sbs
mddev->ro = ro
stop the array:
raid_dtr
md_stop
stop_sync_thread
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
md_wakeup_thread_directly(mddev->sync_thread);
wait_event(…, !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
sync thread done:
md_do_sync
set_bit(MD_RECOVERY_DONE, &mddev->recovery);
md_wakeup_thread(mddev->thread);
daemon thread can’t unregister sync thread:
md_check_recovery
if (!md_is_rdwr(mddev) &&
!test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
return;
-> -> MD_RECOVERY_RUNNING can’t be cleared, hence step 4 hang;

The root cause is that dm-raid manipulate ‘mddev->ro’ by itself,
however, dm-raid really should stop sync thread before setting the
array read-only. Unfortunately, I need to read more code before I
can refacter the handler of ‘mddev->ro’ in dm-raid, hence let’s fix
the problem the easy way for now to prevent dm-raid regression.

Affected configurations

Vulners

Node

linuxlinux_kernelRange4.8–6.7.7

linuxlinux_kernelRange6.8.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/md/md.c"
    ],
    "versions": [
      {
        "version": "ecbfb9f118bc",
        "lessThan": "2ea169c5a0b1",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "ecbfb9f118bc",
        "lessThan": "55a48ad2db64",
        "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/md.c"
    ],
    "versions": [
      {
        "version": "4.8",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "4.8",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.7",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]