CVE-2024-26924

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_set_pipapo: do not free live element

Pablo reports a crash with large batches of elements with a

back-to-back add/remove pattern. Quoting Pablo:

add_elem("00000000") timeout 100 ms

...

add_elem("0000000X") timeout 100 ms

del_elem("0000000X") <---------------- delete one that was just added

...

add_elem("00005000") timeout 100 ms

1) nft_pipapo_remove() removes element 0000000X

Then, KASAN shows a splat.

Looking at the remove function there is a chance that we will drop a

rule that maps to a non-deactivated element.

Removal happens in two steps, first we do a lookup for key k and return the

to-be-removed element and mark it as inactive in the next generation.

Then, in a second step, the element gets removed from the set/map.

The _remove function does not work correctly if we have more than one

element that share the same key.

This can happen if we insert an element into a set when

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References