CVE-2026-64563

/// Technical description

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

rhashtable: clear stale iter->p on table restart

rhashtable_walk_start_check() has two restart paths when resuming a walk.

When iter->walker.tbl is valid, it re-validates iter->p against the table

and sets iter->p = NULL if the object is gone. When iter->walker.tbl is

NULL (table was freed during resize), it resets slot and skip but forgets

to clear iter->p.

rhashtable_walk_next() then dereferences the stale iter->p, reading

freed memory. This is a use-after-free.

Any caller that does multi-fragment rhashtable walks across

walk_stop/walk_start boundaries is affected. Concrete cases include

netlink_diag (__netlink_diag_dump in net/netlink/diag.c) and TIPC

(tipc_nl_sk_walk in net/tipc/socket.c).

Crash stack (netlink_diag):

BUG: KASAN: slab-use-after-free in rhashtable_walk_next+0x365/0x3c0

Read of size 8 at addr ffff88801a9d2438 (freed kmalloc-2k, offset 1080)

Call Trace:

rhashtable_walk_next+0x365/0x3c0

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References