{"id":"CVE-2024-42102","summary":"Revert \"mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again\"","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nRevert \"mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again\"\n\nPatch series \"mm: Avoid possible overflows in dirty throttling\".\n\nDirty throttling logic assumes dirty limits in page units fit into\n32-bits.  This patch series makes sure this is true (see patch 2/2 for\nmore details).\n\n\nThis patch (of 2):\n\nThis reverts commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78.\n\nThe commit is broken in several ways.  Firstly, the removed (u64) cast\nfrom the multiplication will introduce a multiplication overflow on 32-bit\narchs if wb_thresh * bg_thresh \u003e= 1\u003c\u003c32 (which is actually common - the\ndefault settings with 4GB of RAM will trigger this).  Secondly, the\ndiv64_u64() is unnecessarily expensive on 32-bit archs.  We have\ndiv64_ul() in case we want to be safe & cheap.  Thirdly, if dirty\nthresholds are larger than 1\u003c\u003c32 pages, then dirty balancing is going to\nblow up in many other spectacular ways anyway so trying to fix one\npossible overflow is just moot.","modified":"2026-03-20T12:38:41.255757Z","published":"2024-07-30T07:45:58.423Z","related":["ALSA-2024:6567","MGASA-2024-0277","MGASA-2024-0278","SUSE-SU-2024:4314-1","SUSE-SU-2024:4316-1","SUSE-SU-2024:4318-1","SUSE-SU-2024:4387-1","SUSE-SU-2025:20163-1","SUSE-SU-2025:20164-1","SUSE-SU-2025:20246-1","SUSE-SU-2025:20247-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/42xxx/CVE-2024-42102.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/000099d71648504fb9c7a4616f92c2b70c3e44ec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/145faa3d03688cbb7bbaaecbd84c01539852942c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/23a28f5f3f6ca1e4184bd0e9631cd0944cf1c807"},{"type":"WEB","url":"https://git.kernel.org/stable/c/253f9ea7e8e53a5176bd80ceb174907b10724c1a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2820005edae13b140f2d54267d1bd6bb23915f59"},{"type":"WEB","url":"https://git.kernel.org/stable/c/30139c702048f1097342a31302cbd3d478f50c63"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cbbe17a324437c0ff99881a3ee453da45b228a00"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f6620df12cb6bdcad671d269debbb23573502f9d"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/42xxx/CVE-2024-42102.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-42102"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c593d26fb5d577ef31b6e49a31e08ae3ebc1bc1e"},{"fixed":"253f9ea7e8e53a5176bd80ceb174907b10724c1a"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1f12e4b3284d6c863f272eb2de0d4248ed211cf4"},{"fixed":"23a28f5f3f6ca1e4184bd0e9631cd0944cf1c807"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"81e7d2530d458548b90a5c5e76b77ad5e5d1c0df"},{"fixed":"145faa3d03688cbb7bbaaecbd84c01539852942c"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5099871b370335809c0fd1abad74d9c7c205d43f"},{"fixed":"2820005edae13b140f2d54267d1bd6bb23915f59"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"16b1025eaa8fc223ab4273ece20d1c3a4211a95d"},{"fixed":"cbbe17a324437c0ff99881a3ee453da45b228a00"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ec18ec230301583395576915d274b407743d8f6c"},{"fixed":"f6620df12cb6bdcad671d269debbb23573502f9d"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9319b647902cbd5cc884ac08a8a6d54ce111fc78"},{"fixed":"000099d71648504fb9c7a4616f92c2b70c3e44ec"},{"fixed":"30139c702048f1097342a31302cbd3d478f50c63"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"65977bed167a92e87085e757fffa5798f7314c9f"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-42102.json"}}],"schema_version":"1.7.5"}