CVE-2026-89948

Summary

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

batman-adv: bla: fix freeing of claims on meshif deletion

When the mesh interface is getting deleted, then batadv_bla_del_backbone_claims() (via batadv_bla_purge_backbone_gw()) could make sure that all claims gets removed. But this function is only executed when bat_priv->bla.claim_hash is not NULL. And since batadv_bla_free() is always setting it to NULL before it is (indirectly) called, it was never actually executed.

But the batadv_bla_purge_claims() -> batadv_handle_unclaim() is at the moment too fragile because the BLA code is not handling the rehashing in batadv_bla_update_orig_address(). The stored backbone address doesn't have to be the one actually used for the hash bucket selection during the initial adding of the backbone. The batadv_handle_unclaim() can therefore fail to find the respective backbone for the unclaim and then stop the deletion.

But the actual backbone_gw object is not needed for the unclaim because all relevant information is always provided by the caller. And the check for the existence of the backbone_gw doesn't provide any additional security check for the deletion of a claim.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/844a95a734f178d56c7acce14c5cce2cecff7e1a
• https://git.kernel.org/stable/c/baeb1a28fd8e2f68193650d3664a8cd1adfd85c6
• https://git.kernel.org/stable/c/aacffa780a37e06cd5a13d33740a6e96c3a67e6c
• https://git.kernel.org/stable/c/76aedcde5a2489cc971d4d1e396e784a49565e96
• https://git.kernel.org/stable/c/f50edb69082a8ba990cc23d642089829f99afe6a
• https://git.kernel.org/stable/c/871acdf97f64cee8398f72b88b89e8b4f4816dbe
• https://git.kernel.org/stable/c/9a0c47023d3254048a1588534755d4476bcc3abc
• https://git.kernel.org/stable/c/8d128c932bced74e3b1625ba3d7c78ef122a88a7

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