linux.git/net/tipc/udp_media.c, branch master

tipc: serialize udp bearer replicast list updates

2026-07-21T18:57:21Z

tipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with list_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs from the encap receive softirq (via tipc_udp_rcast_disc()) without rtnl_lock(), so it can race the cleanup delete and corrupt the list: list_del corruption. prev->next should be ffff8880298d7ab8, but was ffff88802449ad38. (prev=ffff888027e3ec98) kernel BUG at lib/list_debug.c:62! RIP: __list_del_entry_valid_or_report+0x17a/0x200 Workqueue: events cleanup_bearer Call Trace: cleanup_bearer (net/tipc/udp_media.c:811) process_one_work (kernel/workqueue.c:3302) worker_thread (kernel/workqueue.c:3466) The bearer can be enabled from an unprivileged user namespace, as the TIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM. Add a spinlock to struct udp_bearer and take it around the list_add_rcu() in tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so the two writers can no longer corrupt the list. Reject a duplicate peer under the same lock before allocating, and remove tipc_udp_is_known_peer(). The old lockless pre-check in tipc_udp_rcast_disc() was racy: two softirqs discovering the same peer could both find it absent and add it twice. cleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the bearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add() and add a peer after cleanup_bearer() has already emptied the list, leaking that entry when the bearer is freed. Mark the bearer disabled under rcast_lock once the list is emptied and refuse further additions. Fixes: ef20cd4dd163 ("tipc: introduce UDP replicast") Reported-by: Xiang Mei Suggested-by: Tung Nguyen Signed-off-by: Weiming Shi Reviewed-by: Tung Nguyen Link: https://patch.msgid.link/20260716025203.9332-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski

tipc: avoid busy looping in tipc_exit_net()

2026-06-25T15:53:00Z

Blamed commit introduced a busy-wait loop in tipc_exit_net() to wait for pending UDP bearer cleanup works to complete: while (atomic_read(&tn->wq_count)) cond_resched(); This loop can busy-wait for a long time if cond_resched() is a NOP. This typically happens if the netns exit is executed by a high priority task, or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In such cases, it wastes CPU cycles and can lead to soft lockups. Fix this by replacing the busy loop with wait_var_event(), allowing the thread to sleep properly until the work queue count reaches zero. Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and wake_up_var() to wake up the waiter when the count drops to zero. This uses the global wait queue hash table, avoiding the need to bloat struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test() provides the necessary memory barrier to ensure the wakeup is not missed. Fixes: 04c26faa51d1 ("tipc: wait and exit until all work queues are done") Signed-off-by: Eric Dumazet Cc: Jon Maloy Cc: tipc-discussion@lists.sourceforge.net Reviewed-by: Xin Long Link: https://patch.msgid.link/20260623173030.2925059-3-edumazet@google.com Signed-off-by: Jakub Kicinski

tipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()

2026-06-25T15:53:00Z

TIPC UDP media bearer teardown calls dst_cache_destroy() on its replicast caches before calling synchronize_net() to wait for concurrent RCU readers (transmitters) to finish: static void cleanup_bearer(struct work_struct *work) { ... list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) { dst_cache_destroy(&rcast->dst_cache); list_del_rcu(&rcast->list); kfree_rcu(rcast, rcu); } ... dst_cache_destroy(&ub->rcast.dst_cache); udp_tunnel_sock_release(ub->sk); synchronize_net(); ... } This is highly buggy because dst_cache_destroy() immediately frees the per-CPU cache memory (free_percpu()) and releases the cached dst entries without any synchronization. If a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another CPU under RCU protection, it can call dst_cache_get() concurrently, leading to: 1. Use-After-Free on the per-CPU cache pointer itself (crash). 2. "rcuref - imbalanced put()" warning if it attempts to release a dst that was concurrently released by dst_cache_destroy(). Furthermore, calling kfree(ub) immediately after synchronize_net() without closing the socket first (or waiting after closing it) leaves a window where a concurrent receiver (tipc_udp_recv()) could start after synchronize_net(), access ub, and suffer a UAF when kfree(ub) runs. To fix this, we must defer dst_cache_destroy() and kfree(ub) until after we have ensured that no more readers can see the bearer/socket and all existing readers have finished: 1. Defer rcast entry destruction (both dst_cache_destroy() and kfree()) to an RCU callback using call_rcu_hurry(). Using call_rcu_hurry() ensures the dst entries are released quickly. 2. Release the bearer socket using udp_tunnel_sock_release() (stops new receive readers). 3. Call synchronize_net() to wait for all outstanding RCU readers (both transmit and receive) to finish. 4. Now that it is safe, call dst_cache_destroy() on the main bearer cache, and free ub. Note: 3) and 4) can be changed later in net-next to also use call_rcu_hurry() and get rid of the synchronize_net() latency. Fixes: e9c1a793210f ("tipc: add dst_cache support for udp media") Reported-by: syzbot+e14bc5d4942756023b77@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a396a66.52ae72c2.136ac7.0003.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: Jon Maloy Cc: tipc-discussion@lists.sourceforge.net Reviewed-by: Xin Long Link: https://patch.msgid.link/20260623173030.2925059-2-edumazet@google.com Signed-off-by: Jakub Kicinski

tipc: Store struct sock in struct udp_bearer.

2026-05-06T00:47:06Z

tipc udp_bearer does not need to access struct socket itself in the fast path; it only reads struct sock, and struct socket is only used for tunnel setup and teardown. Let's store struct sock directly in struct udp_bearer. Note that cleanup_bearer() calls synchronize_net() after udp_tunnel_sock_release(), so udp_bearer is not freed until inflight fast paths finish. Note also that synchronize_rcu() is added in the error path of tipc_udp_enable() since udp_bearer will be kfree()d immediately once we remove synchronize_rcu() in udp_tunnel_sock_release(). This can be later converted to kfree_rcu(). Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260502031401.3557229-15-kuniyu@google.com Signed-off-by: Jakub Kicinski

udp_tunnel: Pass struct sock to setup_udp_tunnel_sock().

2026-05-06T00:47:04Z

None of the udp_tunnel users need struct socket in their fast paths; it is only used for tunnel setup / teardown. Even setup_udp_tunnel_sock() does not need struct socket. Let's change setup_udp_tunnel_sock() to take struct sock instead of struct socket. Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260502031401.3557229-3-kuniyu@google.com Signed-off-by: Jakub Kicinski

udp_tunnel: Pass struct sock to udp_tunnel_sock_release().

2026-05-06T00:47:03Z

None of the udp_tunnel users need struct socket in their fast paths; it is only used for tunnel setup / teardown. While the UDP tunnel interface accepts struct socket, this encourages users to store the pointer unnecessarily. This leads to extra dereferences when accessing struct sock fields (e.g., sk->sk_user_data instead of sock->sk->sk_user_data). Furthermore, these dereferences necessitate synchronize_rcu() in udp_tunnel_sock_release() to protect the fast paths from sock_orphan() setting sk->sk_socket to NULL. This overhead can be avoided if users store the struct sock pointer directly in their private structures. As a prep, let's change udp_tunnel_sock_release() to take struct sock instead of struct socket. Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260502031401.3557229-2-kuniyu@google.com Signed-off-by: Jakub Kicinski

net: convert remaining ipv6_stub users to direct function calls

2026-03-29T18:21:23Z

As IPv6 is built-in only, the ipv6_stub infrastructure is no longer necessary. Convert remaining ipv6_stub users to make direct function calls. The fallback functions introduced previously will prevent linkage errors when CONFIG_IPV6 is disabled. Signed-off-by: Fernando Fernandez Mancera Tested-by: Ricardo B. Marlière Link: https://patch.msgid.link/20260325120928.15848-9-fmancera@suse.de Signed-off-by: Jakub Kicinski

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-06-19T20:00:24Z

Cross-merge networking fixes after downstream PR (net-6.16-rc3). No conflicts or adjacent changes. Signed-off-by: Jakub Kicinski

tipc: fix null-ptr-deref when acquiring remote ip of ethernet bearer

2025-06-18T21:19:50Z

The reproduction steps: 1. create a tun interface 2. enable l2 bearer 3. TIPC_NL_UDP_GET_REMOTEIP with media name set to tun tipc: Started in network mode tipc: Node identity 8af312d38a21, cluster identity 4711 tipc: Enabled bearer , priority 1 Oops: general protection fault KASAN: null-ptr-deref in range CPU: 1 UID: 1000 PID: 559 Comm: poc Not tainted 6.16.0-rc1+ #117 PREEMPT Hardware name: QEMU Ubuntu 24.04 PC RIP: 0010:tipc_udp_nl_dump_remoteip+0x4a4/0x8f0 the ub was in fact a struct dev. when bid != 0 && skip_cnt != 0, bearer_list[bid] may be NULL or other media when other thread changes it. fix this by checking media_id. Fixes: 832629ca5c313 ("tipc: add UDP remoteip dump to netlink API") Signed-off-by: Haixia Qu Reviewed-by: Tung Nguyen Link: https://patch.msgid.link/20250617055624.2680-1-hxqu@hillstonenet.com Signed-off-by: Jakub Kicinski