Bug 2397555 (CVE-2025-39867)

Summary: CVE-2025-39867 kernel: netfilter: nft_set_pipapo: fix null deref for empty set
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerability-draftAssignee: Product Security DevOps Team <prodsec-dev>
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OS: Linux   
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Description OSIDB Bzimport 2025-09-23 07:01:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_set_pipapo: fix null deref for empty set

Blamed commit broke the check for a null scratch map:
  -  if (unlikely(!m || !*raw_cpu_ptr(m->scratch)))
  +  if (unlikely(!raw_cpu_ptr(m->scratch)))

This should have been "if (!*raw_ ...)".
Use the pattern of the avx2 version which is more readable.

This can only be reproduced if avx2 support isn't available.
Comment 1 Jon Moroney 2025-09-23 17:37:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025092357-CVE-2025-39867-51e2@gregkh/T