net: psp: do not inherit the Rx association on clone

Overview

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

net: psp: do not inherit the Rx association on clone

sk->psp_assoc sits past sk_dontcopy_end, so sock_copy() copies it into every socket accepted from a listener without taking a reference, while inet_sock_destruct() puts for every inet socket. psp_twsk_init() does refcount_inc() for the timewait socket, so a child closing through TIME_WAIT cancels its own put and leaves the association with one reference and N timewait sockets holding the same pointer. Closing the listener frees it, and the timewait timers then put freed memory.

Rejecting the association on a listening socket is not sufficient: a socket can acquire one while established and then be turned back into a listener, because tcp_disconnect() leaves sk->psp_assoc in place.

BUG: KASAN: slab-use-after-free in psp_twsk_assoc_free+0x6f/0xf0 Write of size 4 at addr ffff888110f9255c by task swapper/7/0 psp_twsk_assoc_free+0x6f/0xf0 inet_twsk_put+0xda/0x1b0 call_timer_fn+0x53/0x2e0 __run_timers+0x764/0xa80 Freed by task 99: kfree+0x1a7/0x500 process_one_work+0x7ec/0x1100

An association carries a per-connection SPI and key, so a child must not inherit the parent's. Clear it on clone.

Affected

• Linux >= 6b46ca260e2290e3453d1355ab5b6d283d73d780 < a9f14ea73e82db743f0acf4219f499d594589288
• Linux >= 6b46ca260e2290e3453d1355ab5b6d283d73d780 < c962695467d3ab9738a6508279827ec33a7d2bdf
• Linux >= 6b46ca260e2290e3453d1355ab5b6d283d73d780 < 1d2929d0850fff683b8aff051275945e65f082c8
• Linux 6.18

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.