CVE-2026-64563rhashtable: clear stale iter->p on table restart

Official 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 (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

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/ba510b5e9fe396497d31162acb579f210adfe6c8
• https://git.kernel.org/stable/c/a0406c40c6638c5ae50257db6297b2fba6c9ba16
• https://git.kernel.org/stable/c/0955b65c2b47c30b439e2cf1b1e375073aa0413a
• https://git.kernel.org/stable/c/c39643ad99fea749be50615550e8f0e6d6e60694
• https://git.kernel.org/stable/c/042fda5c088015f18838e5c692659a7be60aeb26
• https://git.kernel.org/stable/c/3ff7c1dbf722cf3fa538672452ba182318e0fcc3
• https://git.kernel.org/stable/c/4169d9fb92f313ff8e7e83d733c1ecdcc93eebd3
• https://git.kernel.org/stable/c/8173f7e2ce67e6ca1d4763f3da14e5b01ce77456