sched/fair: Fix overflow in update_tg_cfs_runnable()
Summary
| CVE | CVE-2026-93182 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-17 17:18:14 UTC |
| Updated | 2026-09-17 17:18:14 UTC |
| Description | In 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] <TASK> [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) |
Risk And Classification
EPSS: 0.002050000 probability, percentile 0.109320000 (date 2026-09-19)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 39d707097a0820c6e87eff4195f0940e8ff1147e git | Not specified |
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75 git | Not specified |
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 7cc237e3bc1733928313d2462b413ae441b0eef3 git | Not specified |
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 18fdd0978ec3dda0ff6865cd273e47e022180710 git | Not specified |
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 f94e62d21faad5e244d0874598a4d0ebbc0ea405 git | Not specified |
| CNA | Linux | Linux | affected 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 4f166adb5cb0525d9e32d45729fd8f28c80acbee git | Not specified |
| CNA | Linux | Linux | affected 5.17 | Not specified |
| CNA | Linux | Linux | unaffected 5.17 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.188 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.157 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.110 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.52 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2.6 7.2.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.3-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/7cc237e3bc1733928313d2462b413ae441b0eef3 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/18fdd0978ec3dda0ff6865cd273e47e022180710 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/f94e62d21faad5e244d0874598a4d0ebbc0ea405 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4f166adb5cb0525d9e32d45729fd8f28c80acbee | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/39d707097a0820c6e87eff4195f0940e8ff1147e | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.