Bug 2418832 (CVE-2025-40240)

Summary: CVE-2025-40240 kernel: sctp: avoid NULL dereference when chunk data buffer is missing
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 2025-12-04 16:03:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sctp: avoid NULL dereference when chunk data buffer is missing

chunk->skb pointer is dereferenced in the if-block where it's supposed
to be NULL only.

chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list
instead and do it just before replacing chunk->skb. We're sure that
otherwise chunk->skb is non-NULL because of outer if() condition.
Comment 1 Alexander B 2025-12-05 15:29:30 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025120403-CVE-2025-40240-745a@gregkh/T