Linux Kernel Vulnerability in Batman-adv Impacting Gateway References

CVE-2026-31657

What is CVE-2026-31657?

A vulnerability in the batman-adv component of the Linux kernel can lead to improper management of backbone gateway references. The function batadv_bla_add_claim() may inadvertently replace a claim’s backbone gateway and drop the last reference to the previous gateway while active readers are still accessing this pointer. This situation can cause instability and unexpected behavior as the netlink claim dump path could dereference a non-existent pointer. The batadv_bla_check_claim() function continues to exhibit unsafe pointer access patterns. To mitigate this issue, it is critical that functionalities are revised to reuse batadv_bla_claim_get_backbone_gw() for all readers, ensuring a stable reference to the gateway until all related operations are complete.

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