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GHSA-2VH7-793M-F7HF

Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-15 15:30

Details

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. ]

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74571"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T13:18:02Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\n  Call Trace:\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\n   open_ctree+0xc6e/0x1ca0 [btrfs]\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\n\nThe same crash occurs with a corrupted raid stripe tree root, via\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\n\n[CAUSE]\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\nwhen either root cannot be read, leaving the corresponding root pointer\nNULL while its on-disk feature bit remains set.\n\nbtrfs_update_global_block_rsv() then dereferences the missing root based\non the feature bit alone.\n\n[FIX]\nRescue mounts are fully read-only and cannot start transactions, so the\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\nreserve as full and return before performing the accounting.\n\nAnd since we need to check if the fs is mount fully RO, export\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\n\n[ Squash the fs_is_full_ro() export commit into this one. ]",
  "id": "GHSA-2vh7-793m-f7hf",
  "modified": "2026-08-15T15:30:36Z",
  "published": "2026-08-15T15:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74571"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-74571 (GCVE-0-2026-74571)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:28 – Updated: 2026-08-17 05:22

Title

btrfs: skip global block reserve accounting for rescue mounts

Summary

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. ]

Severity

No CVSS data available.

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/076349e4c8d11f6b5…
https://git.kernel.org/stable/c/51a0e839985862144…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 8dbfc14fc736eb701089aff09645c3d4ad3decb1 , < 076349e4c8d11f6b58c4549976a513b2b4dc6df2 (git) Affected: 8dbfc14fc736eb701089aff09645c3d4ad3decb1 , < 51a0e8399858621442807a26057bcd1cd3ced046 (git) Affected: cbec34d3021d47007a0334c634f7053dbaf93d02 (git) Affected: 1e8087589b5cf6fa17adaf57b64cf1656d77dfec (git) Affected: 6.1.43 , < 6.2 (semver) Affected: 6.4.8 , < 6.5 (semver)
Linux	Linux	Affected: 6.5 Unaffected: 0 , < 6.5 (semver) Unaffected: 7.1.8 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/block-rsv.c",
            "fs/btrfs/disk-io.c",
            "fs/btrfs/fs.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "076349e4c8d11f6b58c4549976a513b2b4dc6df2",
              "status": "affected",
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              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "cbec34d3021d47007a0334c634f7053dbaf93d02",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1e8087589b5cf6fa17adaf57b64cf1656d77dfec",
              "versionType": "git"
            },
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              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.43",
              "versionType": "semver"
            },
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              "status": "affected",
              "version": "6.4.8",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/block-rsv.c",
            "fs/btrfs/disk-io.c",
            "fs/btrfs/fs.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.8",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\n  Call Trace:\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\n   open_ctree+0xc6e/0x1ca0 [btrfs]\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\n\nThe same crash occurs with a corrupted raid stripe tree root, via\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\n\n[CAUSE]\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\nwhen either root cannot be read, leaving the corresponding root pointer\nNULL while its on-disk feature bit remains set.\n\nbtrfs_update_global_block_rsv() then dereferences the missing root based\non the feature bit alone.\n\n[FIX]\nRescue mounts are fully read-only and cannot start transactions, so the\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\nreserve as full and return before performing the accounting.\n\nAnd since we need to check if the fs is mount fully RO, export\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\n\n[ Squash the fs_is_full_ro() export commit into this one. ]"
        }
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          "url": "https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046"
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    "datePublished": "2026-08-15T12:28:10.711Z",
    "dateReserved": "2026-08-15T05:44:03.917Z",
    "dateUpdated": "2026-08-17T05:22:00.523Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-2VH7-793M-F7HF

CVE-2026-74571 (GCVE-0-2026-74571)

Tags

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Nomenclature