CVE-2026-68117

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

tipc: clear sock->sk on the failed-insert path in tipcskcreate()

When tipcskcreate() fails to insert the new socket (tipcskinsert()

returns non-zero), its error path frees the sk with sk_free() but leaves

sock->sk pointing at the freed object:

if (tipcskinsert(tsk)) {

sk_free(sk);

pr_warn("Socket create failed; port number exhausted\n");

return -EINVAL;

}

This is harmless for plain socket(): the syscall layer clears sock->ops

before releasing, so tipc_release() is never called. It is not harmless

on the accept() path. tipc_accept() creates the pre-allocated child

socket with tipcskcreate(net, new_sock, 0, kern); on failure it leaves

newsock->sk dangling and newsock->ops non-NULL, and do_accept() then

fput()s the new file, so _sockrelease() -> tipc_release() runs

locksock(newsock->sk) on the freed sk -- a use-after-free write of the

sk_lock spinlock.

tipc_release() already guards this exact "failed accept() releases a

pre-allocated child" case with "if (sk == NULL) return 0;", but the

guard is bypassed because tipcskcreate() left sock->sk non-NULL

(dangling) rather than NULL.

Clear sock->sk on the failed-insert path so the existing tipc_release()

NULL check fires and the use-after-free is avoided.

The tipcskinsert() failure is reached when the per-netns socket

rhashtable hits its maxsize (tskrhtparams.maxsize = 1048576, ~2M

elements) -- i.e. once a netns holds ~2M TIPC sockets every insert

returns -E2BIG.

  BUG: KASAN: slab-use-after-free in locksocknested (net/core/sock.c:3839)

  Write of size 8 at addr ffff8880047cdc38 by task init/1

   locksocknested (net/core/sock.c:3839)

   tipc_release (net/tipc/socket.c:638)

   _sockrelease (net/socket.c:710)

   sock_close (net/socket.c:1501)

   _fput (fs/filetable.c:512)

  Allocated by task 1:

   sk_alloc (net/core/sock.c:2308)

   tipcskcreate (net/tipc/socket.c:487)

   tipc_accept (net/tipc/socket.c:2744)

   do_accept (net/socket.c:2034)

  Freed by task 1:

   _skdestruct (net/core/sock.c:2391)

   tipcskcreate (net/tipc/socket.c:504)

   tipc_accept (net/tipc/socket.c:2744)

   do_accept (net/socket.c:2034)