ipmr: account multicast table and route memory

Summary

In the Linux kernel, the following vulnerability has been resolved: ipmr: account multicast table and route memory A netadmin in a user+net namespace can create many IPv4 and IPv6 multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen id allocates an mr_table via the shared mr_table_alloc(), links it into the per-net list, and leaves it until netns teardown. Those objects were not charged to memcg, so the host unreclaimable slab grows with the table count. Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established handling of IP addresses, routes and alternate interface names. Unresolved MFC entries are still allocated from softIRQ with GFP_ATOMIC and are not charged. They expire after 10 seconds and are bounded by the socket receive queue; see commit 0079ad8e8dc3 ("ipmr: remove hard code cache_resolve_queue_len limit").

Timeline

1. Sep 25, 2026, 10:22 AM UTCCVE published
2. Oct 21, 2026, 12:53 PM UTCRecord last updated

Affected versions

• Linux Linux

  From f0ad0860d01e47a3ffd220564c5c653b3afbe962 · fixed in 21e0749e8ef272ac7e3eefe0fa488a5983f4b038; From f0ad0860d01e47a3ffd220564c5c653b3afbe962 · fixed in ec1c6140394ee87127479bc500a3158b125bf07a; From f0ad0860d01e47a3ffd220564c5c653b3afbe962 · fixed in 0264b3ee09b118fec8a5471b4ca288f8ab84722f; From f0ad0860d01e47a3ffd220564c5c653b3afbe962 · fixed in d0a2e2a4ee6bfe51e398bfb6921a7d0f4c26bc1c; From f0ad0860d01e47a3ffd220564c5c653b3afbe962 · fixed in b7ee18725f2292ab554aa96a101ae42d45f008bd

• Linux Linux

  2.6.35

• KernelLinux

  From 2.6.35 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7

References 5