GHSA-8VPP-69HW-PQMM
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32In the Linux kernel, the following vulnerability has been resolved:
sched/fair: Fix overflow in update_tg_cfs_runnable()
A divide-by-zero crash is observed when running hackbench:
[14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+ [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0 [14697.506799] [14697.507411] __dequeue_task+0x2b4/0xc70 [14697.508677] dequeue_task_fair+0x36/0x370 [14697.509047] dequeue_task+0x101/0x2f0 [14697.509426] __schedule+0x1b1/0x1a00 [14697.510868] anon_pipe_read+0x3da/0x450 [14697.511400] vfs_read+0x361/0x390 [14697.512053] __x64_sys_read+0x19/0x30
The divide-by-zero happens here:
if (scale_load_down(gcfs_rq->load.weight)) { load_sum = div_u64(gcfs_rq->avg.load_sum, scale_load_down(gcfs_rq->load.weight)); }
gcfs_rq->load.weight is an insane large value and is truncated to the lower 32 bits by div_u64, which happen to be 0.
Using AI for investigation, the cause is a u32 overflow in update_tg_cfs_runnable(), and flat pickup became a victim when using tg_tasks():
u32 new_sum, divider; ... new_sum = se->avg.runnable_avg * divider; <-- boom
The following sequence shows how this triggers the crash:
propagate_entity_load_avg() update_tg_cfs_runnable() # u32 overflow corrupts runnable_sum
__update_load_avg_cfs_rq() ___update_load_avg() # computes insane runnable_avg update_tg_load_avg() # propagates to tg->runnable_avg
update_cfs_group() calc_concur_shares() tg_tasks() # long-to-int truncation, negative nr reweight_entity() # corrupted se->load.weight update_load_add() # corrupted cfs_rq->load.weight
propagate_entity_load_avg() update_tg_cfs_load() div_u64() # divide-by-zero
Fix by widening new_sum from u32 to u64 (no need to force tg_tasks() to return unsigned long after this fix)
{
"affected": [],
"aliases": [
"CVE-2026-93182"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:18:14Z",
"severity": null
},
"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)",
"id": "GHSA-8vpp-69hw-pqmm",
"modified": "2026-09-17T18:32:13Z",
"published": "2026-09-17T18:32:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93182"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
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