CVE-2026-98487net: bridge: mdb: restart port group walk after deletion

Official description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mdb: restart port group walk after deletion br_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking mp->ports. br_multicast_del_pg() can re-enter the same MDB entry through br_multicast_sg_del_exclude_ports() and unlink other port groups. If the cursor points into one of those groups, the next iteration dereferences a stale cursor and can leave mp->ports pointing at freed memory. A following RTM_GETMDB exposes the dangling pointer: BUG: KASAN: slab-use-after-free in br_mdb_dump Read of size 8 br_mdb_dump rtnl_mdb_dump rtnl_dumpit netlink_dump Reset the cursor to mp->ports after every deletion. The deletion removes at least the selected group, so the restarted walk always makes progress.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/46ec55855c972504258c371677ac039ba20e5d12
• https://git.kernel.org/stable/c/ab3c4a4c85f2e1e8d04b5c1770dea8412d21c7fe
• https://git.kernel.org/stable/c/fe2a42789c12eb7c5d3a42191e2cc735a6c35ead
• https://git.kernel.org/stable/c/ab1404ac81154a89fb61ac50ae9a04cd8d4834dc