batman-adv: mcast: linearize skbuff for packet generation

Summary

In the Linux kernel, the following vulnerability has been resolved: batman-adv: mcast: linearize skbuff for packet generation batadv_mcast_forw_packet() and batadv_mcast_forw_scrape() is not only called (indirectly) by the unsharing+linearizing batadv_recv_mcast_packet() handler. When it is called (indirectly) by batadv_mcast_forw_mcsend() then it will be unshared but not linearized. The SKB_LINEAR_ASSERT() can therefore cause a fatal BUG(). The linearization should happen during the expansion of the head because the scrape function can be hit already during the initial batadv_mcast_forw_mode() selection code: • batadv_interface_tx • batadv_mcast_forw_mode • batadv_mcast_forw_mode_by_count() • batadv_mcast_forw_push() -> calls batadv_mcast_forw_expand_head() before everything else • batadv_mcast_forw_push_tvlvs() • batadv_mcast_forw_push_dests() • batadv_mcast_forw_push_adjust_padding() • batadv_mcast_forw_scrape()

Timeline

1. Sep 16, 2026, 10:32 AM UTCCVE published
2. Oct 19, 2026, 8:55 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 90039133221e33964ccb4a536dad7eb0a372fff7 · fixed in a9603e0a7cb5e0cddc6b23af153cf7daafc5c55e; From 90039133221e33964ccb4a536dad7eb0a372fff7 · fixed in c32e5e25c41201c8c3b796a4ab2c45103187091e; From 90039133221e33964ccb4a536dad7eb0a372fff7 · fixed in 2879177539e3ece483a8e5406970373698e9a6c5; From 90039133221e33964ccb4a536dad7eb0a372fff7 · fixed in 6a30a59e2660afd03c975f1b8eae6a2301161197

• Linux Linux

  6.8

• KernelLinux

  From 6.8.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.5

References 4