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Resource Leak Affecting kernel-headers package, versions *

Severity

 Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (12th percentile)

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  • Snyk IDSNYK-RHEL9-KERNELHEADERS-6677345
  • published27 Apr 2024
  • disclosed24 Apr 2024
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Introduced: 24 Apr 2024

CVE-2024-26924  (opens in a new tab)
CWE-402  (opens in a new tab)
First added by Snyk

How to fix?

There is no fixed version for RHEL:9 kernel-headers.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-headers package and not the kernel-headers package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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 the set already holds an element with same key, but the element mapping to the existing key has timed out or is not active in the next generation.

In such case its possible that removal will unmap the wrong element. If this happens, we will leak the non-deactivated element, it becomes unreachable.

The element that got deactivated (and will be freed later) will remain reachable in the set data structure, this can result in a crash when such an element is retrieved during lookup (stale pointer).

Add a check that the fully matching key does in fact map to the element that we have marked as inactive in the deactivation step. If not, we need to continue searching.

Add a bug/warn trap at the end of the function as well, the remove function must not ever be called with an invisible/unreachable/non-existent element.

v2: avoid uneeded temporary variable (Stefano)

References

CVSS Scores

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