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btrfs: skip global block reserve accounting for rescue mounts

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: btrfs: skip global block reserve accounting for rescue mounts [BUG] Mounting with rescue=ibadroots after corrupting the block group tree root triggers a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000100 RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs] Call Trace: fill_dummy_bgs+0xd4/0x120 [btrfs] open_ctree+0xc6e/0x1ca0 [btrfs] btrfs_get_tree+0x50d/0xa40 [btrfs] The same crash occurs with a corrupted raid stripe tree root, via btrfs_read_block_groups() instead of fill_dummy_bgs(). [CAUSE] With rescue=ibadroots, btrfs_read_roots() allows the mount to continue when either root cannot be read, leaving the corresponding root pointer NULL while its on-disk feature bit remains set. btrfs_update_global_block_rsv() then dereferences the missing root based on the feature bit alone. [FIX] Rescue mounts are fully read-only and cannot start transactions, so the global reserve is never consumed. Under btrfs_is_full_ro(), mark the reserve as full and return before performing the accounting. And since we need to check if the fs is mount fully RO, export fs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h. [ Squash the fs_is_full_ro() export commit into this one. ]

Announced Source revision 1
Original source ↗

CVE-2026-74571

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74571

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
        "lessThan": "ca05d9abde2195cec3d07d0d4d65152d8171078f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
        "lessThan": "3a69fae2371a5ee190d4c4bbe5304a753558c1c6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
        "lessThan": "969a96479add6bd42d7f7241f99f27b31571a953",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "076349e4c8d11f6b58c4549976a513b2b4dc6df2",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "51a0e8399858621442807a26057bcd1cd3ced046",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cbec34d3021d47007a0334c634f7053dbaf93d02",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1e8087589b5cf6fa17adaf57b64cf1656d77dfec",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6.1.43",
        "lessThan": "6.2",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "6.4.8",
        "lessThan": "6.5",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/btrfs/block-rsv.c",
      "fs/btrfs/disk-io.c",
      "fs/btrfs/fs.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6.5"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "6.5",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.114",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.57",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.8",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/btrfs/block-rsv.c",
      "fs/btrfs/disk-io.c",
      "fs/btrfs/fs.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74571

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46579 · Revision 1
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