Bug 2394651 (CVE-2025-39742)

Summary: CVE-2025-39742 kernel: RDMA: hfi1: fix possible divide-by-zero in find_hw_thread_mask()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-11 17:04:52 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA: hfi1: fix possible divide-by-zero in find_hw_thread_mask()

The function divides number of online CPUs by num_core_siblings, and
later checks the divider by zero. This implies a possibility to get
and divide-by-zero runtime error. Fix it by moving the check prior to
division. This also helps to save one indentation level.
Comment 1 Mauro Matteo Cascella 2025-09-15 07:40:25 UTC 
Upstream advisory;
https://lore.kernel.org/linux-cve-announce/2025091139-CVE-2025-39742-37e8@gregkh/T