kernel/linux.git/include/net/sctp, branch v6.1.168

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

2025-04-25T08:43:43+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: add a refcnt in sctp_stream_priorities to avoid a nested loop

2023-03-11T12:55:26+00:00

[ Upstream commit 68ba44639537de6f91fe32783766322d41848127 ] With this refcnt added in sctp_stream_priorities, we don't need to traverse all streams to check if the prio is used by other streams when freeing one stream's prio in sctp_sched_prio_free_sid(). This can avoid a nested loop (up to 65535 * 65535), which may cause a stuck as Ying reported: watchdog: BUG: soft lockup - CPU#23 stuck for 26s! [ksoftirqd/23:136] Call Trace: sctp_sched_prio_free_sid+0xab/0x100 [sctp] sctp_stream_free_ext+0x64/0xa0 [sctp] sctp_stream_free+0x31/0x50 [sctp] sctp_association_free+0xa5/0x200 [sctp] Note that it doesn't need to use refcount_t type for this counter, as its accessing is always protected under the sock lock. v1->v2: - add a check in sctp_sched_prio_set to avoid the possible prio_head refcnt overflow. Fixes: 9ed7bfc79542 ("sctp: fix memory leak in sctp_stream_outq_migrate()") Reported-by: Ying Xu Acked-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Link: https://lore.kernel.org/r/825eb0c905cb864991eba335f4a2b780e543f06b.1677085641.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: fix memory leak in sctp_stream_outq_migrate()

2022-11-29T16:30:50+00:00

When sctp_stream_outq_migrate() is called to release stream out resources, the memory pointed to by prio_head in stream out is not released. The memory leak information is as follows: unreferenced object 0xffff88801fe79f80 (size 64): comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) hex dump (first 32 bytes): 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ backtrace: [] kmalloc_trace+0x26/0x60 [] sctp_sched_prio_set+0x4cc/0x770 [] sctp_stream_init_ext+0xd2/0x1b0 [] sctp_sendmsg_to_asoc+0x1614/0x1a30 [] sctp_sendmsg+0xda1/0x1ef0 [] inet_sendmsg+0x9d/0xe0 [] sock_sendmsg+0xd3/0x120 [] __sys_sendto+0x23a/0x340 [] __x64_sys_sendto+0xe1/0x1b0 [] do_syscall_64+0x39/0xb0 [] entry_SYSCALL_64_after_hwframe+0x63/0xcd Link: https://syzkaller.appspot.com/bug?exrid=29c402e56c4760763cc0 Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao Reviewed-by: Xin Long Link: https://lore.kernel.org/r/20221126031720.378562-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski

net: remove noblock parameter from recvmsg() entities

2022-04-12T13:00:25+00:00

The internal recvmsg() functions have two parameters 'flags' and 'noblock' that were merged inside skb_recv_datagram(). As a follow up patch to commit f4b41f062c42 ("net: remove noblock parameter from skb_recv_datagram()") this patch removes the separate 'noblock' parameter for recvmsg(). Analogue to the referenced patch for skb_recv_datagram() the 'flags' and 'noblock' parameters are unnecessarily split up with e.g. err = sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT, flags & ~MSG_DONTWAIT, &addr_len); or in err = INDIRECT_CALL_2(sk->sk_prot->recvmsg, tcp_recvmsg, udp_recvmsg, sk, msg, size, flags & MSG_DONTWAIT, flags & ~MSG_DONTWAIT, &addr_len); instead of simply using only flags all the time and check for MSG_DONTWAIT where needed (to preserve for the formerly separated no(n)block condition). Signed-off-by: Oliver Hartkopp Link: https://lore.kernel.org/r/20220411124955.154876-1-socketcan@hartkopp.net Signed-off-by: Paolo Abeni

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

2022-01-05T22:36:10+00:00

No conflicts. Signed-off-by: Jakub Kicinski

sctp: hold endpoint before calling cb in sctp_transport_lookup_process

2022-01-02T12:46:41+00:00

The same fix in commit 5ec7d18d1813 ("sctp: use call_rcu to free endpoint") is also needed for dumping one asoc and sock after the lookup. Fixes: 86fdb3448cc1 ("sctp: ensure ep is not destroyed before doing the dump") Signed-off-by: Xin Long Signed-off-by: David S. Miller

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

2021-12-30T20:12:12+00:00

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c commit 077cdda764c7 ("net/mlx5e: TC, Fix memory leak with rules with internal port") commit 31108d142f36 ("net/mlx5: Fix some error handling paths in 'mlx5e_tc_add_fdb_flow()'") commit 4390c6edc0fb ("net/mlx5: Fix some error handling paths in 'mlx5e_tc_add_fdb_flow()'") https://lore.kernel.org/all/20211229065352.30178-1-saeed@kernel.org/ net/smc/smc_wr.c commit 49dc9013e34b ("net/smc: Use the bitmap API when applicable") commit 349d43127dac ("net/smc: fix kernel panic caused by race of smc_sock") bitmap_zero()/memset() is removed by the fix Signed-off-by: Jakub Kicinski

sctp: use call_rcu to free endpoint

2021-12-25T17:13:37+00:00

This patch is to delay the endpoint free by calling call_rcu() to fix another use-after-free issue in sctp_sock_dump(): BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 Call Trace: __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] __lock_sock+0x203/0x350 net/core/sock.c:2253 lock_sock_nested+0xfe/0x120 net/core/sock.c:2774 lock_sock include/net/sock.h:1492 [inline] sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324 sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091 sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527 __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049 inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065 netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244 __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352 netlink_dump_start include/linux/netlink.h:216 [inline] inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170 __sock_diag_cmd net/core/sock_diag.c:232 [inline] sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274 This issue occurs when asoc is peeled off and the old sk is freed after getting it by asoc->base.sk and before calling lock_sock(sk). To prevent the sk free, as a holder of the sk, ep should be alive when calling lock_sock(). This patch uses call_rcu() and moves sock_put and ep free into sctp_endpoint_destroy_rcu(), so that it's safe to try to hold the ep under rcu_read_lock in sctp_transport_traverse_process(). If sctp_endpoint_hold() returns true, it means this ep is still alive and we have held it and can continue to dump it; If it returns false, it means this ep is dead and can be freed after rcu_read_unlock, and we should skip it. In sctp_sock_dump(), after locking the sk, if this ep is different from tsp->asoc->ep, it means during this dumping, this asoc was peeled off before calling lock_sock(), and the sk should be skipped; If this ep is the same with tsp->asoc->ep, it means no peeloff happens on this asoc, and due to lock_sock, no peeloff will happen either until release_sock. Note that delaying endpoint free won't delay the port release, as the port release happens in sctp_endpoint_destroy() before calling call_rcu(). Also, freeing endpoint by call_rcu() makes it safe to access the sk by asoc->base.sk in sctp_assocs_seq_show() and sctp_rcv(). Thanks Jones to bring this issue up. v1->v2: - improve the changelog. - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed. Reported-by: syzbot+9276d76e83e3bcde6c99@syzkaller.appspotmail.com Reported-by: Lee Jones Fixes: d25adbeb0cdb ("sctp: fix an use-after-free issue in sctp_sock_dump") Signed-off-by: Xin Long Signed-off-by: David S. Miller

sctp: move hlist_node and hashent out of sctp_ep_common

2021-12-23T11:15:30+00:00

Struct sctp_ep_common is included in both asoc and ep, but hlist_node and hashent are only needed by ep after asoc_hashtable was dropped by Commit b5eff7128366 ("sctp: drop the old assoc hashtable of sctp"). So it is better to move hlist_node and hashent from sctp_ep_common to sctp_endpoint, and it saves some space for each asoc. Signed-off-by: Xin Long Signed-off-by: David S. Miller

sctp: make the raise timer more simple and accurate

2021-11-26T05:00:45+00:00

Currently, the probe timer is reused as the raise timer when PLPMTUD is in the Search Complete state. raise_count was introduced to count how many times the probe timer has timed out. When raise_count reaches to 30, the raise timer handler will be triggered. During the whole processing above, the timer keeps timing out every probe_ interval. It is a waste for the Search Complete state, as the raise timer only needs to time out after 30 * probe_interval. Since the raise timer and probe timer are never used at the same time, it is no need to keep probe timer 'alive' in the Search Complete state. This patch to introduce sctp_transport_reset_raise_timer() to start the timer as the raise timer when entering the Search Complete state. When entering the other states, sctp_transport_reset_probe_timer() will still be called to reset the timer to the probe timer. raise_count can be removed from sctp_transport as no need to count probe timer timeout for raise timer timeout. last_rtx_chunks can be removed as sctp_transport_reset_probe_timer() can be called in the place where asoc rtx_data_chunks is changed. Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://lore.kernel.org/r/edb0e48988ea85997488478b705b11ddc1ba724a.1637781974.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski