{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-50217", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-10-21T19:36:19.972Z", "datePublished": "2024-11-09T10:14:28.798Z", "dateUpdated": "2026-08-05T11:42:34.683Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:42:34.683Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()\n\nMounting btrfs from two images (which have the same one fsid and two\ndifferent dev_uuids) in certain executing order may trigger an UAF for\nvariable 'device->bdev_file' in __btrfs_free_extra_devids(). And\nfollowing are the details:\n\n1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs\n devices by ioctl(BTRFS_IOC_SCAN_DEV):\n\n / btrfs_device_1 → loop0\n fs_device\n \\ btrfs_device_2 → loop1\n2. mount /dev/loop0 /mnt\n btrfs_open_devices\n btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0)\n btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)\n btrfs_fill_super\n open_ctree\n fail: btrfs_close_devices // -ENOMEM\n\t btrfs_close_bdev(btrfs_device_1)\n fput(btrfs_device_1->bdev_file)\n\t // btrfs_device_1->bdev_file is freed\n\t btrfs_close_bdev(btrfs_device_2)\n fput(btrfs_device_2->bdev_file)\n\n3. mount /dev/loop1 /mnt\n btrfs_open_devices\n btrfs_get_bdev_and_sb(&bdev_file)\n // EIO, btrfs_device_1->bdev_file is not assigned,\n // which points to a freed memory area\n btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)\n btrfs_fill_super\n open_ctree\n btrfs_free_extra_devids\n if (btrfs_device_1->bdev_file)\n fput(btrfs_device_1->bdev_file) // UAF !\n\nFix it by setting 'device->bdev_file' as 'NULL' after closing the\nbtrfs_device in btrfs_close_one_device()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerability is reached only through local block-device operations — `mount(2)` of a btrfs volume plus device registration via `BTRFS_IOC_SCAN_DEV`/`device=` — on a locally attached device or loop-mounted image. No network or remote-peer data is involved.\nAC:L - The attacker fully controls both filesystem images and the order of the two mounts; the first mount's `open_ctree()` failure can be forced deterministically by corrupting the superblock/chunk tree rather than relying on the ENOMEM fault injection in the report, and no race must be won. Heap grooming of the `filp` slab between the two mounts is entirely under attacker control.\nPR:N - The attacker supplies only the malicious images (USB stick, disk image file, or loop-backed file) and needs no account or privilege on the target system; the privileged mount is performed by the victim or by an automounter such as udisks2 on the attacker's behalf.\nUI:R - Exploitation requires the victim (or an automount daemon acting for a logged-in user) to mount the attacker's crafted btrfs images, twice in sequence, since btrfs lacks `FS_USERNS_MOUNT` and cannot be mounted directly by an unprivileged attacker.\nS:U - The corruption and its consequences are confined to the kernel of the same system; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The stray `fput()` on a freed `struct file` in a `SLAB_TYPESAFE_BY_RCU` cache causes a live file's refcount to be dropped, yielding a reusable use-after-free object that can be leveraged for arbitrary kernel memory disclosure.\nI:H - The same reference-count underflow gives a premature-free UAF on `struct file`, a well-established primitive for heap spraying, arbitrary write, and control-flow hijack leading to privilege escalation.\nA:H - Even without full exploitation the `fput()` on freed memory corrupts the slab and reliably produces a KASAN splat, refcount BUG, or kernel panic, taking the system down." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/volumes.c" ], "versions": [ { "version": "142388194191a3edc9ba01cfcfd8b691e0971fb2", "lessThan": "47a83f8df39545f3f552bb6a1b6d9c30e37621dd", "status": "affected", "versionType": "git" }, { "version": "142388194191a3edc9ba01cfcfd8b691e0971fb2", "lessThan": "aec8e6bf839101784f3ef037dcdb9432c3f32343", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/volumes.c" ], "versions": [ { "version": "4.8", "status": "affected" }, { "version": "0", "lessThan": "4.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.7", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8", "versionEndExcluding": "6.11.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.8", "versionEndExcluding": "6.12" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/47a83f8df39545f3f552bb6a1b6d9c30e37621dd" }, { "url": "https://git.kernel.org/stable/c/aec8e6bf839101784f3ef037dcdb9432c3f32343" } ], "title": "btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2024-50217", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2024-12-11T14:25:44.077787Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-12-11T14:58:32.841Z" } }, { "title": "CVE Program Container", "references": [ { "url": "http://www.openwall.com/lists/oss-security/2025/04/10/4" }, { "url": "http://www.openwall.com/lists/oss-security/2025/04/10/5" }, { "url": "http://www.openwall.com/lists/oss-security/2025/04/10/6" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-04-11T00:11:26.593Z" } } ] } }