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CVE-2026-98942— sched_ext: Build the cid tables privately and publish them with RCU

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： sched_ext：在私有上下文中构建 cid 表，并通过 RCU 机制发布 cid 表在修改过程中对 cid kfuncs（内核函数）可见：首次启用时，全局指针在填充完成前就已发布； 会就地重写这些指针；重新启用时则会就地重建。此时，若存在竞态的 TRACING 或 SYSCALL 程序，可能会读取到未填充的条目，包括 kmalloc 分配的表中未初始化的内存，或出现拓扑更新撕裂（torn topo updates）的问题。 修复方案将 cid 表的生命周期绑定到根调

AI Predicted 6.5 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1069.006
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I. Basic Information for CVE-2026-98942

Vulnerability Information
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Vulnerability Title
sched_ext: Build the cid tables privately and publish them with RCU
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Build the cid tables privately and publish them with RCU The cid tables are visible to the cid kfuncs while being modified: the first enable publishes the global pointers before filling them, ops.init_cids() overrides rewrite them in place, and re-enables rebuild them in place. A racing TRACING or SYSCALL program can read unfilled entries, including uninitialized memory in the kmalloc'd tables, or torn topo updates. Tie the tables' lifetimes to the root sched instead: each root enable builds a fresh set privately and publishes the per-table __rcu globals once the layout is final, and root disable unpublishes and RCU-frees the set. A non-NULL global is now always a fully built table which stays valid for the reader's RCU read section, and lookups stay two loads. Kfuncs treat NULL as no-mapping, also after the scheduler exits instead of reporting the stale last mapping. The cid kfuncs are available whether the root scheduler is cid-form or cpu-form, the latter to allow gradual migration to cids. Every root therefore builds and publishes a default mapping. Every reader must either be gated on scheduler liveness or NULL-check inside an RCU read section. Fix the two kfuncs that were neither: scx_bpf_this_cid() read the table with no RCU or preemption protection and scx_bpf_task_cid() relied on KF_RCU, which doesn't put a sleepable program in an RCU read section. The hotplug callbacks are instead serialized by retiring the tables inside the cpus_read_lock() section that clears scx_root. v2: Document why every root builds the tables (desc + cid.c comment).
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ 0e1a74369bdbc357d3d9713734418d914a981553 -
Linux Linux 7.2.10 ~ 7.2.* -

II. Public POCs for CVE-2026-98942

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III. Intelligence Information for CVE-2026-98942

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Other References for CVE-2026-98942 (2)

Same Patch Batch · Linux · 2026-10-23 · 218 CVEs total

CVE-2026-98937 perf/core: Check kernel access when kernel callchains are requested
CVE-2026-98951 riscv: ptrace: Zero-initialize regset buffers before copyin
CVE-2026-98950 flow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect()
CVE-2026-98949 drm/imagination: Fix reference and vm_bo handling in remap()
CVE-2026-98948 mlxsw: spectrum_flower: Fix port range register leak in tmplt_create()
CVE-2026-98947 vsock: Fix memory leak in vmci_transport_recv_dgram_cb()
CVE-2026-98946 drm/vc4: Disable the V3D interrupt across runtime suspend
CVE-2026-98945 HID: steam: Rearrange teardown sequence
CVE-2026-98944 HID: steam: Refactor registration
CVE-2026-98943 HID: steam: Clean up locking
CVE-2026-98941 ext4: don't enable large folios on encrypted inodes
CVE-2026-98940 ASoC: qcom: lpass-cpu: use DAI table index for playback constraints
CVE-2026-98939 x86/mm: Drop unnecessary PMD page copy when freeing
CVE-2026-98938 rust: irq: pass RegistrationInner as cookie to request_irq
CVE-2026-98926 drm/amd/display: Remove sink usage from DPMS
CVE-2026-98929 macsec: initialize SecY before registering the netdevice
CVE-2026-98928 KVM: arm64: Derive GUEST_HAS_SVE from the SVE feature bit at EL2
CVE-2026-98927 KVM: arm64: nv: Fix life cycle of the nested_mmus array
CVE-2026-98930 KVM: s390: Fix IRQ injection with SIGP Stop and Store Status
CVE-2026-98925 bpf, sockmap: Fix self-redirect copied_seq double-counting

Showing top 20 of 218 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98942

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