CVE-2026-74571

Full vulnerability record from the local CVENow database.

Description

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

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

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

Published

2026-08-15 13:18:02.733000

Last modified

2026-10-30 13:20:02.770000

View original CVE JSON

{
  "id": "CVE-2026-74571",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-08-15T13:18:02.733",
  "lastModified": "2026-10-30T13:20:02.770",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "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. ]"
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "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",
          "versions": [
            {
              "version": "cbec34d3021d47007a0334c634f7053dbaf93d02",
              "lessThan": "aa72cc4675240ab6b01ec72ac6a1fe832e715569",
              "versionType": "git",
              "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"
            },
            {
              "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
              "lessThan": "076349e4c8d11f6b58c4549976a513b2b4dc6df2",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "8dbfc14fc736eb701089aff09645c3d4ad3decb1",
              "lessThan": "51a0e8399858621442807a26057bcd1cd3ced046",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1e8087589b5cf6fa17adaf57b64cf1656d77dfec",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "6.1.43",
              "lessThan": "6.1.191",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "6.4.8",
              "lessThan": "6.5",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "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",
          "versions": [
            {
              "version": "6.5",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.5",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.160",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.114",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.57",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1.8",
              "lessThanOrEqual": "7.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3a69fae2371a5ee190d4c4bbe5304a753558c1c6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/969a96479add6bd42d7f7241f99f27b31571a953",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/aa72cc4675240ab6b01ec72ac6a1fe832e715569",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ca05d9abde2195cec3d07d0d4d65152d8171078f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}