{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-56581", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T14:03:06.000Z", "datePublished": "2024-12-27T14:23:23.193Z", "dateUpdated": "2026-08-05T11:45:11.349Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:45:11.349Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: ref-verify: fix use-after-free after invalid ref action\n\nAt btrfs_ref_tree_mod() after we successfully inserted the new ref entry\n(local variable 'ref') into the respective block entry's rbtree (local\nvariable 'be'), if we find an unexpected action of BTRFS_DROP_DELAYED_REF,\nwe error out and free the ref entry without removing it from the block\nentry's rbtree. Then in the error path of btrfs_ref_tree_mod() we call\nbtrfs_free_ref_cache(), which iterates over all block entries and then\ncalls free_block_entry() for each one, and there we will trigger a\nuse-after-free when we are called against the block entry to which we\nadded the freed ref entry to its rbtree, since the rbtree still points\nto the block entry, as we didn't remove it from the rbtree before freeing\nit in the error path at btrfs_ref_tree_mod(). Fix this by removing the\nnew ref entry from the rbtree before freeing it.\n\nSyzbot report this with the following stack traces:\n\n BTRFS error (device loop0 state EA): Ref action 2, root 5, ref_root 0, parent 8564736, owner 0, offset 0, num_refs 18446744073709551615\n __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523\n update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512\n btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594\n btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754\n btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116\n btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4314\n btrfs_insert_empty_item fs/btrfs/ctree.h:669 [inline]\n btrfs_insert_orphan_item+0x1f1/0x320 fs/btrfs/orphan.c:23\n btrfs_orphan_add+0x6d/0x1a0 fs/btrfs/inode.c:3482\n btrfs_unlink+0x267/0x350 fs/btrfs/inode.c:4293\n vfs_unlink+0x365/0x650 fs/namei.c:4469\n do_unlinkat+0x4ae/0x830 fs/namei.c:4533\n __do_sys_unlinkat fs/namei.c:4576 [inline]\n __se_sys_unlinkat fs/namei.c:4569 [inline]\n __x64_sys_unlinkat+0xcc/0xf0 fs/namei.c:4569\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n BTRFS error (device loop0 state EA): Ref action 1, root 5, ref_root 5, parent 0, owner 260, offset 0, num_refs 1\n __btrfs_mod_ref+0x76b/0xac0 fs/btrfs/extent-tree.c:2521\n update_ref_for_cow+0x96a/0x11f0\n btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594\n btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754\n btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116\n btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411\n __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030\n btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1114 [inline]\n __btrfs_commit_inode_delayed_items+0x2318/0x24a0 fs/btrfs/delayed-inode.c:1137\n __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171\n btrfs_commit_transaction+0x8a8/0x3740 fs/btrfs/transaction.c:2313\n prepare_to_relocate+0x3c4/0x4c0 fs/btrfs/relocation.c:3586\n relocate_block_group+0x16c/0xd40 fs/btrfs/relocation.c:3611\n btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4081\n btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3377\n __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4161\n btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4538\n BTRFS error (device loop0 state EA): Ref action 2, root 5, ref_root 0, parent 8564736, owner 0, offset 0, num_refs 18446744073709551615\n __btrfs_mod_ref+0x7dd/0xac0 fs/btrfs/extent-tree.c:2523\n update_ref_for_cow+0x9cd/0x11f0 fs/btrfs/ctree.c:512\n btrfs_force_cow_block+0x9f6/0x1da0 fs/btrfs/ctree.c:594\n btrfs_cow_block+0x35e/0xa40 fs/btrfs/ctree.c:754\n btrfs_search_slot+0xbdd/0x30d0 fs/btrfs/ctree.c:2116\n btrfs_lookup_inode+0xdc/0x480 fs/btrfs/inode-item.c:411\n __btrfs_update_delayed_inode+0x1e7/0xb90 fs/btrfs/delayed-inode.c:1030\n btrfs_update_delayed_i\n---truncated---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached only through local filesystem activity on a mounted btrfs volume — ordinary syscalls such as unlinkat() or the BTRFS_IOC_BALANCE ioctl driving btrfs_cow_block()/__btrfs_mod_ref(). There is no network-facing path into fs/btrfs/ref-verify.c.\nAC:H - Exploitation requires the kernel to be built with CONFIG_BTRFS_FS_REF_VERIFY, which is default-n developer-only instrumentation not shipped by any mainstream distribution, AND the filesystem to be mounted with the explicit -o ref_verify option; without either, btrfs_ref_tree_mod() returns immediately. Both are target-configuration conditions entirely outside the attacker's control.\nPR:L - On a ref_verify-instrumented mount whose extent tree is inconsistent, the syzbot stack traces show the faulting path entered from a plain unlinkat() syscall via btrfs_orphan_add() → btrfs_cow_block() → __btrfs_mod_ref(), so an unprivileged local user performing normal file operations suffices; no capability check guards that path.\nUI:N - Once the instrumented filesystem is mounted, the attacker triggers the invalid ref action entirely through their own syscalls with no action from any other user or administrator.\nS:U - The use-after-free and double free occur in kernel slab memory managed by the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - free_block_entry() performs rb_first()/rb_entry() reads on the freed 64-byte ref_entry, so an attacker who grooms the kmalloc-64 slab to reclaim that object during the unlocked window controls the rbtree pointers being dereferenced, yielding a controlled kernel memory read primitive and disclosure of arbitrary kernel data.\nI:H - rb_erase() writes parent/color pointers into the freed object and its rbtree neighbours after the free, and the object is then kfree()'d a second time; this combination of a post-free write and a double free is a classic route to heap metadata corruption, arbitrary write, and control-flow hijack.\nA:H - The bug is a KASAN-confirmed slab-use-after-free followed by a double free, which reliably oopses or panics the kernel and corrupts the slab allocator state, 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/ref-verify.c" ], "versions": [ { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "dfb9fe7de61f34cc241ab3900bdde93341096e0e", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "6fd018aa168e472ce35be32296d109db6adb87ea", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "d2b85ce0561fde894e28fa01bd5d32820d585006", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "6370db28af9a8ae3bbdfe97f8a48f8f995e144cf", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "4275ac2741941c9c7c2293619fdbacb9f70ba85b", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "a6f9e7a0bf1185c9070c0de03bb85eafb9abd650", "status": "affected", "versionType": "git" }, { "version": "fd708b81d972a0714b02a60eb4792fdbf15868c4", "lessThan": "7c4e39f9d2af4abaf82ca0e315d1fd340456620f", "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/ref-verify.c" ], "versions": [ { "version": "4.15", "status": "affected" }, { "version": "0", "lessThan": "4.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.287", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.231", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.174", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.120", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.64", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.4", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "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": "4.15", "versionEndExcluding": "5.4.287" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "5.10.231" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "5.15.174" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.1.120" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.6.64" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.12.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/dfb9fe7de61f34cc241ab3900bdde93341096e0e" }, { "url": "https://git.kernel.org/stable/c/6fd018aa168e472ce35be32296d109db6adb87ea" }, { "url": "https://git.kernel.org/stable/c/d2b85ce0561fde894e28fa01bd5d32820d585006" }, { "url": "https://git.kernel.org/stable/c/6370db28af9a8ae3bbdfe97f8a48f8f995e144cf" }, { "url": "https://git.kernel.org/stable/c/4275ac2741941c9c7c2293619fdbacb9f70ba85b" }, { "url": "https://git.kernel.org/stable/c/a6f9e7a0bf1185c9070c0de03bb85eafb9abd650" }, { "url": "https://git.kernel.org/stable/c/7c4e39f9d2af4abaf82ca0e315d1fd340456620f" } ], "title": "btrfs: ref-verify: fix use-after-free after invalid ref action", "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-2024-56581", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2025-02-11T15:42:39.280771Z" } } } ], "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": "2025-02-11T15:45:24.590Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:49:58.257Z" } } ] } }