kernel/linux.git/net/sctp/socket.c, branch v6.12.80

sctp: Defer SCTP_DBG_OBJCNT_DEC() to sctp_destroy_sock().

2025-12-18T12:54:48+00:00

[ Upstream commit 622e8838a29845316668ec2e7648428878df7f9a ] SCTP_DBG_OBJCNT_INC() is called only when sctp_init_sock() returns 0 after successfully allocating sctp_sk(sk)->ep. OTOH, SCTP_DBG_OBJCNT_DEC() is called in sctp_close(). The code seems to expect that the socket is always exposed to userspace once SCTP_DBG_OBJCNT_INC() is incremented, but there is a path where the assumption is not true. In sctp_accept(), sctp_sock_migrate() could fail after sctp_init_sock(). Then, sk_common_release() does not call inet_release() nor sctp_close(). Instead, it calls sk->sk_prot->destroy(). Let's move SCTP_DBG_OBJCNT_DEC() from sctp_close() to sctp_destroy_sock(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Acked-by: Xin Long Link: https://patch.msgid.link/20251023231751.4168390-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: Do not wake readers in __sctp_write_space()

2025-06-27T10:11:29+00:00

[ Upstream commit af295892a7abbf05a3c2ba7abc4d81bb448623d6 ] Function __sctp_write_space() doesn't set poll key, which leads to ep_poll_callback() waking up all waiters, not only these waiting for the socket being writable. Set the key properly using wake_up_interruptible_poll(), which is preferred over the sync variant, as writers are not woken up before at least half of the queue is available. Also, TCP does the same. Signed-off-by: Petr Malat Acked-by: Xin Long Link: https://patch.msgid.link/20250516081727.1361451-1-oss@malat.biz Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: detect and prevent references to a freed transport in sendmsg

2025-04-20T08:15:50+00:00

commit f1a69a940de58b16e8249dff26f74c8cc59b32be upstream. sctp_sendmsg() re-uses associations and transports when possible by doing a lookup based on the socket endpoint and the message destination address, and then sctp_sendmsg_to_asoc() sets the selected transport in all the message chunks to be sent. There's a possible race condition if another thread triggers the removal of that selected transport, for instance, by explicitly unbinding an address with setsockopt(SCTP_SOCKOPT_BINDX_REM), after the chunks have been set up and before the message is sent. This can happen if the send buffer is full, during the period when the sender thread temporarily releases the socket lock in sctp_wait_for_sndbuf(). This causes the access to the transport data in sctp_outq_select_transport(), when the association outqueue is flushed, to result in a use-after-free read. This change avoids this scenario by having sctp_transport_free() signal the freeing of the transport, tagging it as "dead". In order to do this, the patch restores the "dead" bit in struct sctp_transport, which was removed in commit 47faa1e4c50e ("sctp: remove the dead field of sctp_transport"). Then, in the scenario where the sender thread has released the socket lock in sctp_wait_for_sndbuf(), the bit is checked again after re-acquiring the socket lock to detect the deletion. This is done while holding a reference to the transport to prevent it from being freed in the process. If the transport was deleted while the socket lock was relinquished, sctp_sendmsg_to_asoc() will return -EAGAIN to let userspace retry the send. The bug was found by a private syzbot instance (see the error report [1] and the C reproducer that triggers it [2]). Link: https://people.igalia.com/rcn/kernel_logs/20250402__KASAN_slab-use-after-free_Read_in_sctp_outq_select_transport.txt [1] Link: https://people.igalia.com/rcn/kernel_logs/20250402__KASAN_slab-use-after-free_Read_in_sctp_outq_select_transport__repro.c [2] Cc: stable@vger.kernel.org Fixes: df132eff4638 ("sctp: clear the transport of some out_chunk_list chunks in sctp_assoc_rm_peer") Suggested-by: Xin Long Signed-off-by: Ricardo Cañuelo Navarro Acked-by: Xin Long Link: https://patch.msgid.link/20250404-kasan_slab-use-after-free_read_in_sctp_outq_select_transport__20250404-v1-1-5ce4a0b78ef2@igalia.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

sctp: ensure sk_state is set to CLOSED if hashing fails in sctp_listen_start

2024-10-09T12:36:32+00:00

If hashing fails in sctp_listen_start(), the socket remains in the LISTENING state, even though it was not added to the hash table. This can lead to a scenario where a socket appears to be listening without actually being accessible. This patch ensures that if the hashing operation fails, the sk_state is set back to CLOSED before returning an error. Note that there is no need to undo the autobind operation if hashing fails, as the bind port can still be used for next listen() call on the same socket. Fixes: 76c6d988aeb3 ("sctp: add sock_reuseport for the sock in __sctp_hash_endpoint") Reported-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: set sk_state back to CLOSED if autobind fails in sctp_listen_start

2024-10-03T10:18:29+00:00

In sctp_listen_start() invoked by sctp_inet_listen(), it should set the sk_state back to CLOSED if sctp_autobind() fails due to whatever reason. Otherwise, next time when calling sctp_inet_listen(), if sctp_sk(sk)->reuse is already set via setsockopt(SCTP_REUSE_PORT), sctp_sk(sk)->bind_hash will be dereferenced as sk_state is LISTENING, which causes a crash as bind_hash is NULL. KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:sctp_inet_listen+0x7f0/0xa20 net/sctp/socket.c:8617 Call Trace: __sys_listen_socket net/socket.c:1883 [inline] __sys_listen+0x1b7/0x230 net/socket.c:1894 __do_sys_listen net/socket.c:1902 [inline] Fixes: 5e8f3f703ae4 ("sctp: simplify sctp listening code") Reported-by: syzbot+f4e0f821e3a3b7cee51d@syzkaller.appspotmail.com Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/a93e655b3c153dc8945d7a812e6d8ab0d52b7aa0.1727729391.git.lucien.xin@gmail.com Signed-off-by: Paolo Abeni

sctp: cancel a blocking accept when shutdown a listen socket

2024-07-03T08:45:39+00:00

As David Laight noticed, "In a multithreaded program it is reasonable to have a thread blocked in accept(). With TCP a subsequent shutdown(listen_fd, SHUT_RDWR) causes the accept to fail. But nothing happens for SCTP." sctp_disconnect() is eventually called when shutdown a listen socket, but nothing is done in this function. This patch sets RCV_SHUTDOWN flag in sk->sk_shutdown there, and adds the check (sk->sk_shutdown & RCV_SHUTDOWN) to break and return in sctp_accept(). Note that shutdown() is only supported on TCP-style SCTP socket. Reported-by: David Laight Signed-off-by: Xin Long Signed-off-by: David S. Miller

net: change proto and proto_ops accept type

2024-05-14T00:19:09+00:00

Rather than pass in flags, error pointer, and whether this is a kernel invocation or not, add a struct proto_accept_arg struct as the argument. This then holds all of these arguments, and prepares accept for being able to pass back more information. No functional changes in this patch. Acked-by: Jakub Kicinski Signed-off-by: Jens Axboe

sctp: prefer struct_size over open coded arithmetic

2024-04-30T09:39:03+00:00

This is an effort to get rid of all multiplications from allocation functions in order to prevent integer overflows [1][2]. As the "ids" variable is a pointer to "struct sctp_assoc_ids" and this structure ends in a flexible array: struct sctp_assoc_ids { [...] sctp_assoc_t gaids_assoc_id[]; }; the preferred way in the kernel is to use the struct_size() helper to do the arithmetic instead of the calculation "size + size * count" in the kmalloc() function. Also, refactor the code adding the "ids_size" variable to avoid sizing twice. This way, the code is more readable and safer. This code was detected with the help of Coccinelle, and audited and modified manually. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1] Link: https://github.com/KSPP/linux/issues/160 [2] Signed-off-by: Erick Archer Acked-by: Xin Long Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/PAXPR02MB724871DB78375AB06B5171C88B152@PAXPR02MB7248.eurprd02.prod.outlook.com Signed-off-by: Paolo Abeni

net: add sk_wake_async_rcu() helper

2024-03-29T22:03:11+00:00

While looking at UDP receive performance, I saw sk_wake_async() was no longer inlined. This matters at least on AMD Zen1-4 platforms (see SRSO) This might be because rcu_read_lock() and rcu_read_unlock() are no longer nops in recent kernels ? Add sk_wake_async_rcu() variant, which must be called from contexts already holding rcu lock. As SOCK_FASYNC is deprecated in modern days, use unlikely() to give a hint to the compiler. sk_wake_async_rcu() is properly inlined from __udp_enqueue_schedule_skb() and sock_def_readable(). Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20240328144032.1864988-5-edumazet@google.com Signed-off-by: Jakub Kicinski

net: introduce include/net/rps.h

2024-03-08T05:12:43+00:00

Move RPS related structures and helpers from include/linux/netdevice.h and include/net/sock.h to a new include file. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20240306160031.874438-18-edumazet@google.com Signed-off-by: Jakub Kicinski