Linux Kernel UAF in rhashtable Walk
CVE-2026-64563 Published on August 4, 2026
rhashtable: clear stale iter->p on table restart
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 (lib/rhashtable.c:1016)
__netlink_diag_dump+0x160/0x760 (net/netlink/diag.c:122)
netlink_diag_dump+0xc2/0x240
netlink_dump+0x5bc/0x1270
netlink_recvmsg+0x7a3/0x980
sock_recvmsg+0x1bc/0x200
__sys_recvfrom+0x1d4/0x2c0
Products Associated with CVE-2026-64563
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Affected Versions
Linux:- Version 5d240a8936f6a1d3ece06701e8c4d830a2eca8a8 and below 3ff7c1dbf722cf3fa538672452ba182318e0fcc3 is affected.
- Version 5d240a8936f6a1d3ece06701e8c4d830a2eca8a8 and below 4169d9fb92f313ff8e7e83d733c1ecdcc93eebd3 is affected.
- Version 5d240a8936f6a1d3ece06701e8c4d830a2eca8a8 and below 8173f7e2ce67e6ca1d4763f3da14e5b01ce77456 is affected.
- Version 4.18 is affected.
- Before 4.18 is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc5, <= * is unaffected.