{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47638", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-02-26T01:48:21.519Z", "datePublished": "2025-02-26T01:54:11.178Z", "dateUpdated": "2026-08-05T08:48:43.826Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:48:43.826Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nubifs: rename_whiteout: Fix double free for whiteout_ui->data\n\n'whiteout_ui->data' will be freed twice if space budget fail for\nrename whiteout operation as following process:\n\nrename_whiteout\n dev = kmalloc\n whiteout_ui->data = dev\n kfree(whiteout_ui->data) // Free first time\n iput(whiteout)\n ubifs_free_inode\n kfree(ui->data)\t // Double free!\n\nKASAN reports:\n==================================================================\nBUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70\nCall Trace:\n kfree+0x117/0x490\n ubifs_free_inode+0x4f/0x70 [ubifs]\n i_callback+0x30/0x60\n rcu_do_batch+0x366/0xac0\n __do_softirq+0x133/0x57f\n\nAllocated by task 1506:\n kmem_cache_alloc_trace+0x3c2/0x7a0\n do_rename+0x9b7/0x1150 [ubifs]\n ubifs_rename+0x106/0x1f0 [ubifs]\n do_syscall_64+0x35/0x80\n\nFreed by task 1506:\n kfree+0x117/0x490\n do_rename.cold+0x53/0x8a [ubifs]\n ubifs_rename+0x106/0x1f0 [ubifs]\n do_syscall_64+0x35/0x80\n\nThe buggy address belongs to the object at ffff88810238bed8 which\nbelongs to the cache kmalloc-8 of size 8\n==================================================================\n\nLet ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused\nassignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode()\n-> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it\n(because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release',\n and the nlink of whiteout inode is 0)." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached via renameat2(RENAME_WHITEOUT) on a mounted UBIFS volume (syscall → vfs_rename → ubifs_rename → do_rename), not via network packet processing.\nAC:L - An attacker with write access can reliably force the whiteout ubifs_budget_space() failure by exhausting free space or concurrent budget pressure after earlier budgets succeed; no conditions outside attacker control are required.\nPR:L - RENAME_WHITEOUT needs only directory write/exec permission; CAP_MKNOD is not required (unprivileged whiteouts since a3c751a50fe6), so a normal local user on writable UBIFS (e.g. Android/embedded data) can trigger it.\nUI:N - The attacker issues renameat2 themselves on an already-mounted writable UBIFS; no separate victim action is required.\nS:U - Impact is confined to the local kernel/host authority (privilege escalation or crash); it does not cross a VM, IOMMU, or other security boundary.\nC:H - This is a double-free of a kmalloc object with an RCU grace period before the second free, enabling heap reclaim and arbitrary read primitives from corrupted allocator/object state.\nI:H - The same double-free/heap corruption is exploitable for arbitrary write and control-flow hijacking via spraying the reclaimed kmalloc-8 slot between the two frees.\nA:H - The double-free triggers KASAN/invalid-free and can oops or panic the kernel even without full exploitation." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ubifs/dir.c" ], "versions": [ { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "8b3c7be16f3f4dfd6e15ac651484e59d3fa36274", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "2b3236ecf96db7af5836e1366ce39ace8ce832fa", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "14276d38c89a170363e90b6ac0a53c3cf61b87fc", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "a90e2dbe66d2647ff95a0442ad2e86482d977fd8", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "2ad07009c459e56ebdcc089d850d664660fdb742", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "b9a937f096e608b3368c1abc920d4d640ba2c94f", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "6d7a158a7363c1f6604aa47ae1a280a5c65123dd", "status": "affected", "versionType": "git" }, { "version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798", "lessThan": "40a8f0d5e7b3999f096570edab71c345da812e3e", "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/ubifs/dir.c" ], "versions": [ { "version": "4.9", "status": "affected" }, { "version": "0", "lessThan": "4.9", "status": "unaffected", "versionType": "semver" }, { "version": "4.14.276", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.238", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.189", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.110", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.33", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.16.19", "lessThanOrEqual": "5.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.17.2", "lessThanOrEqual": "5.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.18", "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": "4.9", "versionEndExcluding": "4.14.276" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "4.19.238" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.4.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.10.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.15.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.16.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.17.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "5.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274" }, { "url": "https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa" }, { "url": "https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc" }, { "url": "https://git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8" }, { "url": "https://git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742" }, { "url": "https://git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f" }, { "url": "https://git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd" }, { "url": "https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e" } ], "title": "ubifs: rename_whiteout: Fix double free for whiteout_ui->data", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47638", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2025-10-01T19:50:47.905064Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-415", "description": "CWE-415 Double Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T19:57:08.545Z" } } ] } }