CVE-2024-57947
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel, in the netfilter module (nf_set_pipapo), there is a bug in the initialization of the fill map during set lookup. The initial buffer is initialized to all-ones, but the restriction to the size of the first field is missing, causing bit leakage into subsequent rounds and incorrect matching results for sets where the first field is not the largest.
Risk Assessment
The risk includes incorrect packet filtering behavior, which may lead to improper traffic passing or blocking, potentially violating security policies.
Recommendation
It is recommended to update the Linux kernel to a version containing the fix that correctly initializes the fill map, and run the nft_concat_range.sh selftest after the update.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_set_pipapo: fix initial map fill The initial buffer has to be inited to all-ones, but it must restrict it to the size of the first field, not the total field size. After each round in the map search step, the result and the fill map are swapped, so if we have a set where f->bsize of the first element is smaller than m->bsize_max, those one-bits are leaked into future rounds result map. This makes pipapo find an incorrect matching results for sets where first field size is not the largest. Followup patch adds a test case to nft_concat_range.sh selftest script. Thanks to Stefano Brivio for pointing out that we need to zero out the remainder explicitly, only correcting memset() argument isn't enough.