Bug 2350392 (CVE-2025-21826)

Summary: CVE-2025-21826 kernel: netfilter: nf_tables: reject mismatching sum of field_len with set key length
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: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-03-06 17:01:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: reject mismatching sum of field_len with set key length

The field length description provides the length of each separated key
field in the concatenation, each field gets rounded up to 32-bits to
calculate the pipapo rule width from pipapo_init(). The set key length
provides the total size of the key aligned to 32-bits.

Register-based arithmetics still allows for combining mismatching set
key length and field length description, eg. set key length 10 and field
description [ 5, 4 ] leading to pipapo width of 12.
Comment 1 Mauro Matteo Cascella 2025-03-06 18:26:46 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025030630-CVE-2025-21826-c263@gregkh/T