{ "data_version": "4.0", "data_type": "CVE", "data_format": "MITRE", "CVE_data_meta": { "ID": "CVE-2024-42305", "ASSIGNER": "cve@kernel.org", "STATE": "PUBLIC" }, "description": { "description_data": [ { "lang": "eng", "value": "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." } ] }, "problemtype": { "problemtype_data": [ { "description": [ { "lang": "eng", "value": "n/a" } ] } ] }, "affects": { "vendor": { "vendor_data": [ { "vendor_name": "Linux", "product": { "product_data": [ { "product_name": "Linux", "version": { "version_data": [ { "version_affected": "<", "version_name": "ac27a0ec112a", "version_value": "b80575ffa98b" }, { "version_value": "not down converted", "x_cve_json_5_version_data": { "versions": [ { "version": "2.6.19", "status": "affected" }, { "version": "0", "lessThan": "2.6.19", "status": "unaffected", "versionType": "custom" }, { "version": "4.19.320", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.4.282", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.10.224", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.15.165", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.1.103", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.6.44", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.10.3", "lessThanOrEqual": "6.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.11", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ], "defaultStatus": "affected" } } ] } } ] } } ] } }, "references": { "reference_data": [ { "url": "https://git.kernel.org/stable/c/b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/b80575ffa98b5bb3a5d4d392bfe4c2e03e9557db" }, { "url": "https://git.kernel.org/stable/c/19e13b4d7f0303186fcc891aba8d0de7c8fdbda8", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/19e13b4d7f0303186fcc891aba8d0de7c8fdbda8" }, { "url": "https://git.kernel.org/stable/c/42d420517072028fb0eb852c358056b7717ba5aa", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/42d420517072028fb0eb852c358056b7717ba5aa" }, { "url": "https://git.kernel.org/stable/c/8afe06ed3be7a874b3cd82ef5f8959aca8d6429a", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/8afe06ed3be7a874b3cd82ef5f8959aca8d6429a" }, { "url": "https://git.kernel.org/stable/c/abb411ac991810c0bcbe51c2e76d2502bf611b5c", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/abb411ac991810c0bcbe51c2e76d2502bf611b5c" }, { "url": "https://git.kernel.org/stable/c/9d241b7a39af192d1bb422714a458982c7cc67a2", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/9d241b7a39af192d1bb422714a458982c7cc67a2" }, { "url": "https://git.kernel.org/stable/c/cdd345321699042ece4a9d2e70754d2397d378c5", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/cdd345321699042ece4a9d2e70754d2397d378c5" }, { "url": "https://git.kernel.org/stable/c/50ea741def587a64e08879ce6c6a30131f7111e7", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/50ea741def587a64e08879ce6c6a30131f7111e7" } ] }, "generator": { "engine": "bippy-c9c4e1df01b2" } }