Bug 2404114 (CVE-2025-39990)

Summary: CVE-2025-39990 kernel: bpf: Check the helper function is valid in get_helper_proto
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 2025-10-15 08:02:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Check the helper function is valid in get_helper_proto

kernel test robot reported verifier bug [1] where the helper func
pointer could be NULL due to disabled config option.

As Alexei suggested we could check on that in get_helper_proto
directly. Marking tail_call helper func with BPF_PTR_POISON,
because it is unused by design.

  [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com
Comment 1 Alexander B 2025-10-16 10:37:37 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025101502-CVE-2025-39990-25bc@gregkh/T