{"id":"CVE-2026-93182","summary":"sched/fair: Fix overflow in update_tg_cfs_runnable()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Fix overflow in update_tg_cfs_runnable()\n\nA divide-by-zero crash is observed when running hackbench:\n\n   [14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+\n   [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0\n   [14697.506799]  \u003cTASK\u003e\n   [14697.507411]  __dequeue_task+0x2b4/0xc70\n   [14697.508677]  dequeue_task_fair+0x36/0x370\n   [14697.509047]  dequeue_task+0x101/0x2f0\n   [14697.509426]  __schedule+0x1b1/0x1a00\n   [14697.510868]  anon_pipe_read+0x3da/0x450\n   [14697.511400]  vfs_read+0x361/0x390\n   [14697.512053]  __x64_sys_read+0x19/0x30\n\nThe divide-by-zero happens here:\n\n  if (scale_load_down(gcfs_rq-\u003eload.weight)) {\n           load_sum = div_u64(gcfs_rq-\u003eavg.load_sum,\n                              scale_load_down(gcfs_rq-\u003eload.weight));\n  }\n\ngcfs_rq-\u003eload.weight is an insane large value and is truncated\nto the lower 32 bits by div_u64, which happen to be 0.\n\nUsing AI for investigation, the cause is a u32 overflow in\nupdate_tg_cfs_runnable(), and flat pickup became a victim when using\ntg_tasks():\n\n   u32 new_sum, divider;\n   ...\n   new_sum = se-\u003eavg.runnable_avg * divider; \u003c-- boom\n\nThe following sequence shows how this triggers the crash:\n\n   propagate_entity_load_avg()\n     update_tg_cfs_runnable()     # u32 overflow corrupts runnable_sum\n\n   __update_load_avg_cfs_rq()\n     ___update_load_avg()         # computes insane runnable_avg\n   update_tg_load_avg()           # propagates to tg-\u003erunnable_avg\n\n   update_cfs_group()\n     calc_concur_shares()\n       tg_tasks()                 # long-to-int truncation, negative nr\n     reweight_entity()            # corrupted se-\u003eload.weight\n       update_load_add()          # corrupted cfs_rq-\u003eload.weight\n\n   propagate_entity_load_avg()\n     update_tg_cfs_load()\n       div_u64()                  # divide-by-zero\n\nFix by widening new_sum from u32 to u64 (no need to force tg_tasks()\nto return unsigned long after this fix)","modified":"2026-09-19T03:47:22.813795500Z","published":"2026-09-17T16:12:09.381Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93182.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/18fdd0978ec3dda0ff6865cd273e47e022180710"},{"type":"WEB","url":"https://git.kernel.org/stable/c/39d707097a0820c6e87eff4195f0940e8ff1147e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4f166adb5cb0525d9e32d45729fd8f28c80acbee"},{"type":"WEB","url":"https://git.kernel.org/stable/c/69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7cc237e3bc1733928313d2462b413ae441b0eef3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f94e62d21faad5e244d0874598a4d0ebbc0ea405"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93182.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93182"},{"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":"95246d1ec80b8d19d882cd8eb7ad094e63b41bb8"},{"fixed":"39d707097a0820c6e87eff4195f0940e8ff1147e"},{"fixed":"69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75"},{"fixed":"7cc237e3bc1733928313d2462b413ae441b0eef3"},{"fixed":"18fdd0978ec3dda0ff6865cd273e47e022180710"},{"fixed":"f94e62d21faad5e244d0874598a4d0ebbc0ea405"},{"fixed":"4f166adb5cb0525d9e32d45729fd8f28c80acbee"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93182.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.17.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93182.json"}}],"schema_version":"1.9.0"}