{"id":"CVE-2024-42305","revision":"47ce5f8c38074502a2f5b09c2faa9092","records":[{"revision":"47ce5f8c38074502a2f5b09c2faa9092","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2024-42305","aliases":[],"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 \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":0,"publishedAt":"2024-08-17T09:09:11.296+00:00","modifiedAt":"2026-10-15T00:48:17.796+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/ext4/namei.c\"\n ],\n \"versions\": [\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"19e13b4d7f0303186fcc891aba8d0de7c8fdbda8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"42d420517072028fb0eb852c358056b7717ba5aa\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"8afe06ed3be7a874b3cd82ef5f8959aca8d6429a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"abb411ac991810c0bcbe51c2e76d2502bf611b5c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"9d241b7a39af192d1bb422714a458982c7cc67a2\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"cdd345321699042ece4a9d2e70754d2397d378c5\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n \"lessThan\": \"50ea741def587a64e08879ce6c6a30131f7111e7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"fs/ext4/namei.c\"\n ],\n \"versions\": [\n {\n \"version\": \"2.6.19\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"2.6.19\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"4.19.320\",\n \"lessThanOrEqual\": \"4.19.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.282\",\n \"lessThanOrEqual\": \"5.4.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.224\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.165\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.103\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.44\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.10.3\",\n \"lessThanOrEqual\": \"6.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.11\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db","https://git.kernel.org/stable/c/19e13b4d7f0303186fcc891aba8d0de7c8fdbda8","https://git.kernel.org/stable/c/42d420517072028fb0eb852c358056b7717ba5aa","https://git.kernel.org/stable/c/8afe06ed3be7a874b3cd82ef5f8959aca8d6429a","https://git.kernel.org/stable/c/abb411ac991810c0bcbe51c2e76d2502bf611b5c","https://git.kernel.org/stable/c/9d241b7a39af192d1bb422714a458982c7cc67a2","https://git.kernel.org/stable/c/cdd345321699042ece4a9d2e70754d2397d378c5","https://git.kernel.org/stable/c/50ea741def587a64e08879ce6c6a30131f7111e7"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2024-42305","license":"CVE Program Terms of Use","key":"cve-program:CVE-2024-42305","identifiers":["CVE-2024-42305"]},"retained":false,"historicalAffected":[]}],"coverage":[]}