Bug 2356651 (CVE-2025-21965)

Summary: CVE-2025-21965 kernel: sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-04-01 16:04:29 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()

If a BPF scheduler provides an invalid CPU (outside the nr_cpu_ids
range) as prev_cpu to scx_bpf_select_cpu_dfl() it can cause a kernel
crash.

To prevent this, validate prev_cpu in scx_bpf_select_cpu_dfl() and
trigger an scx error if an invalid CPU is specified.
Comment 1 Robb Gatica 2025-04-02 00:34:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025040145-CVE-2025-21965-34d8@gregkh/T