{"id":"CVE-2024-42305","title":"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 p…","summary":"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 p…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-125"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.20, < 4.19.320","linux_kernel >= 4.20, < 5.4.282","linux_kernel >= 5.5, < 5.10.224","linux_kernel >= 5.11, < 5.15.165","linux_kernel >= 5.16, < 6.1.103","linux_kernel >= 6.2, < 6.6.44","linux_kernel >= 6.7, < 6.10.3","linux_kernel = 2.6.19"],"patched":["linux_kernel 6.10.3"],"published":"2024-08-17","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:18:46.367","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2024-42305","references":[{"url":"https://git.kernel.org/stable/c/19e13b4d7f0303186fcc891aba8d0de7c8fdbda8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/42d420517072028fb0eb852c358056b7717ba5aa","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/50ea741def587a64e08879ce6c6a30131f7111e7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8afe06ed3be7a874b3cd82ef5f8959aca8d6429a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9d241b7a39af192d1bb422714a458982c7cc67a2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/abb411ac991810c0bcbe51c2e76d2502bf611b5c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cdd345321699042ece4a9d2e70754d2397d378c5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://lists.debian.org/debian-lts-announce/2024/10/msg00003.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00226,"epssPercentile":0.13256,"ingestedAt":"2026-10-15T03:30:12.733Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2024-09-10T16:10:19.161352Z"},"slug":"CVE-2024-42305","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 2.6.20, < 4.19.320`\n- `linux_kernel >= 4.20, < 5.4.282`\n- `linux_kernel >= 5.5, < 5.10.224`\n- `linux_kernel >= 5.11, < 5.15.165`\n- `linux_kernel >= 5.16, < 6.1.103`\n- `linux_kernel >= 6.2, < 6.6.44`\n- `linux_kernel >= 6.7, < 6.10.3`\n- `linux_kernel = 2.6.19`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.10.3`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}