{"api_version":"1","generated_at":"2026-07-23T15:33:26+00:00","cve":"CVE-2024-42305","urls":{"html":"https://cve.report/CVE-2024-42305","api":"https://cve.report/api/cve/CVE-2024-42305.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2024-42305","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-42305"},"summary":{"title":"ext4: check dot and dotdot of dx_root before making dir indexed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: check dot and dotdot of dx_root before making dir indexed\n\nSyzbot reports a issue as follows:\n============================================\nBUG: unable to handle page fault for address: ffffed11022e24fe\nPGD 23ffee067 P4D 23ffee067 PUD 0\nOops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI\nCPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0\nCall Trace:\n <TASK>\n make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341\n ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451\n ext4_rename fs/ext4/namei.c:3936 [inline]\n ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214\n[...]\n============================================\n\nThe immediate cause of this problem is that there is only one valid dentry\nfor the block to be split during do_split, so split==0 results in out of\nbounds accesses to the map triggering the issue.\n\n    do_split\n      unsigned split\n      dx_make_map\n       count = 1\n      split = count/2 = 0;\n      continued = hash2 == map[split - 1].hash;\n       ---> map[4294967295]\n\nThe maximum length of a filename is 255 and the minimum block size is 1024,\nso it is always guaranteed that the number of entries is greater than or\nequal to 2 when do_split() is called.\n\nBut syzbot's crafted image has no dot and dotdot in dir, and the dentry\ndistribution in dirblock is as follows:\n\n  bus     dentry1          hole           dentry2           free\n|xx--|xx-------------|...............|xx-------------|...............|\n0   12 (8+248)=256  268     256     524 (8+256)=264 788     236     1024\n\nSo when renaming dentry1 increases its name_len length by 1, neither hole\nnor free is sufficient to hold the new dentry, and make_indexed_dir() is\ncalled.\n\nIn make_indexed_dir() it is assumed that the first two entries of the\ndirblock must be dot and dotdot, so bus and dentry1 are left in dx_root\nbecause they are treated as dot and dotdot, and only dentry2 is moved\nto the new leaf block. That's why count is equal to 1.\n\nTherefore add the ext4_check_dx_root() helper function to add more sanity\nchecks to dot and dotdot before starting the conversion to avoid the above\nissue.","state":"PUBLISHED","assigner":"Linux","published_at":"2024-08-17 09:15:10","updated_at":"2026-05-12 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the Linux kernel, the following vulnerability has been resolved:\n\next4: check dot and dotdot of dx_root before making dir indexed\n\nSyzbot reports a issue as follows:\n============================================\nBUG: unable to handle page fault for address: ffffed11022e24fe\nPGD 23ffee067 P4D 23ffee067 PUD 0\nOops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI\nCPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0\nCall Trace:\n <TASK>\n make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341\n ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451\n ext4_rename fs/ext4/namei.c:3936 [inline]\n ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214\n[...]\n============================================\n\nThe immediate cause of this problem is that there is only one valid dentry\nfor the block to be split during do_split, so split==0 results in out of\nbounds accesses to the map triggering the issue.\n\n    do_split\n      unsigned split\n      dx_make_map\n       count = 1\n      split = count/2 = 0;\n      continued = hash2 == map[split - 1].hash;\n       ---> map[4294967295]\n\nThe maximum length of a filename is 255 and the minimum block size is 1024,\nso it is always guaranteed that the number of entries is greater than or\nequal to 2 when do_split() is called.\n\nBut syzbot's crafted image has no dot and dotdot in dir, and the dentry\ndistribution in dirblock is as follows:\n\n  bus     dentry1          hole           dentry2           free\n|xx--|xx-------------|...............|xx-------------|...............|\n0   12 (8+248)=256  268     256     524 (8+256)=264 788     236     1024\n\nSo when renaming dentry1 increases its name_len length by 1, neither hole\nnor free is sufficient to hold the new dentry, and make_indexed_dir() is\ncalled.\n\nIn make_indexed_dir() it is assumed that the first two entries of the\ndirblock must be dot and dotdot, so bus and dentry1 are left in dx_root\nbecause they are treated as dot and dotdot, and only dentry2 is moved\nto the new leaf block. That's why count is equal to 1.\n\nTherefore add the ext4_check_dx_root() helper function to add more sanity\nchecks to dot and dotdot before starting the conversion to avoid the above\nissue."}],"providerMetadata":{"dateUpdated":"2026-05-11T20:29:48.607Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db"},{"url":"https://git.kernel.org/stable/c/19e13b4d7f0303186fcc891aba8d0de7c8fdbda8"},{"url":"https://git.kernel.org/stable/c/42d420517072028fb0eb852c358056b7717ba5aa"},{"url":"https://git.kernel.org/stable/c/8afe06ed3be7a874b3cd82ef5f8959aca8d6429a"},{"url":"https://git.kernel.org/stable/c/abb411ac991810c0bcbe51c2e76d2502bf611b5c"},{"url":"https://git.kernel.org/stable/c/9d241b7a39af192d1bb422714a458982c7cc67a2"},{"url":"https://git.kernel.org/stable/c/cdd345321699042ece4a9d2e70754d2397d378c5"},{"url":"https://git.kernel.org/stable/c/50ea741def587a64e08879ce6c6a30131f7111e7"}],"title":"ext4: check dot and dotdot of dx_root before making dir indexed","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2024-42305","datePublished":"2024-08-17T09:09:11.296Z","dateReserved":"2024-07-30T07:40:12.273Z","dateUpdated":"2026-05-12T11:56:51.529Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2024-08-17 09:15:10","lastModifiedDate":"2026-05-12 12:17:06","problem_types":["CWE-125"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.20","versionEndExcluding":"4.19.320","matchCriteriaId":"1F2DB4BC-32AC-42D5-A39A-FF732AB5FC96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20","versionEndExcluding":"5.4.282","matchCriteriaId":"A8961D98-9ACF-4188-BA88-44038B14BC28"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.224","matchCriteriaId":"5CCEDF13-293D-4E64-B501-4409D0365AFE"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.165","matchCriteriaId":"B4E2B568-3171-41DE-B519-F2B1A3600D94"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.103","matchCriteriaId":"E45EAC72-8329-4F99-8276-86AF9BB3496A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.44","matchCriteriaId":"CC912330-6B41-4C6B-99AF-F3857FBACB6A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.10.3","matchCriteriaId":"92D388F2-1EAF-4CFA-AC06-5B26D762EA7D"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:-:*:*:*:*:*:*","matchCriteriaId":"9E2DBD4C-9DD9-4DD3-87CB-A0070A789CEA"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:rc2:*:*:*:*:*:*","matchCriteriaId":"8D97ED16-D6B7-4445-889C-4D6DE2EDC49A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:rc3:*:*:*:*:*:*","matchCriteriaId":"B2C2D5D4-9A4B-4CDF-8D71-D22EB5E97D5A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:rc4:*:*:*:*:*:*","matchCriteriaId":"DFFB2843-A867-48EC-97D7-B106C7BBAED0"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:rc5:*:*:*:*:*:*","matchCriteriaId":"3CD3FE23-1A10-47E6-AD7E-D67F1BE3C5E2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:2.6.19:rc6:*:*:*:*:*:*","matchCriteriaId":"9F39FC76-7D77-4064-94D3-A16C436FA8D1"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2024","CveId":"42305","Ordinal":"1","Title":"ext4: check dot and dotdot of dx_root before making dir indexed","CVE":"CVE-2024-42305","Year":"2024"},"notes":[{"CveYear":"2024","CveId":"42305","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: check dot and dotdot of dx_root before making dir indexed\n\nSyzbot reports a issue as follows:\n============================================\nBUG: unable to handle page fault for address: ffffed11022e24fe\nPGD 23ffee067 P4D 23ffee067 PUD 0\nOops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI\nCPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0\nCall Trace:\n <TASK>\n make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341\n ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451\n ext4_rename fs/ext4/namei.c:3936 [inline]\n ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214\n[...]\n============================================\n\nThe immediate cause of this problem is that there is only one valid dentry\nfor the block to be split during do_split, so split==0 results in out of\nbounds accesses to the map triggering the issue.\n\n    do_split\n      unsigned split\n      dx_make_map\n       count = 1\n      split = count/2 = 0;\n      continued = hash2 == map[split - 1].hash;\n       ---> map[4294967295]\n\nThe maximum length of a filename is 255 and the minimum block size is 1024,\nso it is always guaranteed that the number of entries is greater than or\nequal to 2 when do_split() is called.\n\nBut syzbot's crafted image has no dot and dotdot in dir, and the dentry\ndistribution in dirblock is as follows:\n\n  bus     dentry1          hole           dentry2           free\n|xx--|xx-------------|...............|xx-------------|...............|\n0   12 (8+248)=256  268     256     524 (8+256)=264 788     236     1024\n\nSo when renaming dentry1 increases its name_len length by 1, neither hole\nnor free is sufficient to hold the new dentry, and make_indexed_dir() is\ncalled.\n\nIn make_indexed_dir() it is assumed that the first two entries of the\ndirblock must be dot and dotdot, so bus and dentry1 are left in dx_root\nbecause they are treated as dot and dotdot, and only dentry2 is moved\nto the new leaf block. That's why count is equal to 1.\n\nTherefore add the ext4_check_dx_root() helper function to add more sanity\nchecks to dot and dotdot before starting the conversion to avoid the above\nissue.","Type":"Description","Title":"ext4: check dot and dotdot of dx_root before making dir indexed"}]}}}