kernel/git/stable/linux.git/net/sctp/inqueue.c, branch master

sctp: validate chunk length in the inqueue parser

2026-08-30T21:17:53+00:00

SCTP chunks always include a four-byte generic header, but sctp_inq_pop() currently accepts shorter declared lengths. A zero-length chunk leaves chunk_end at the current header. When ASCONF is covered by the association's SCTP-AUTH policy, sctp_assoc_bh_rcv() can continue before the state machine performs its normal chunk-length check. sctp_inq_pop() then returns the same malformed chunk repeatedly and the receive softirq can lock up. A remote SCTP peer can trigger this after establishing an association on a kernel built with CONFIG_IP_SCTP and configured with net.sctp.addip_enable=1 and net.sctp.auth_enable=1. The reproducer did not require application credentials, a shared SCTP AUTH key, or net.sctp.addip_noauth_enable=1. On commit f967455fb2a5 ("seg6: reset IP6CB after IPv6 decapsulation"), one zero-length ASCONF caused repeated watchdog soft-lockup reports in a two-vCPU KVM guest. All 3 pre-trigger health probes succeeded, while 36 of 37 post-trigger probes failed. With this change, all 37 post-trigger probes succeeded and no equivalent soft-lockup signature appeared. Reject chunks shorter than the generic SCTP header at the shared inqueue parser boundary. Mark the packet for discard before either caller can continue processing it, while preserving the four-byte generic minimum. Declared-length 1 through 4 controls and kernel-generated ASCONF traffic remained healthy. The patched sctp_hello selftest passed for IPv4 and IPv6. The complete private reproducer and validation evidence are available directly to maintainers on request. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Cc: stable@vger.kernel.org Signed-off-by: Charles Vosburgh Acked-by: Xin Long Link: https://patch.msgid.link/20260827-sctp-zero-chunk-inqueue-v2-1-2e7669c6a6cb@gmail.com Signed-off-by: Jakub Kicinski

sctp: drop a chunk if its transport was removed

2026-08-20T20:31:09+00:00

sctp_rcv() resolves the transport once per packet and leaves it in chunk->transport. The lookup reference, or the one sctp_add_backlog() takes if the socket is owned by userspace, keeps it around until the chunk has been processed. An authenticated ASCONF DEL-IP can remove it in the meantime. sctp_assoc_rm_peer() takes the transport out of the association and calls sctp_transport_free(), which tags it dead and drops the reference the association held. There is a window on both paths: the packet can sit on the socket backlog, and on the direct path the lookup completes before bh_lock_sock(). The DATA chunk in that packet puts the removed transport back into asoc->peer.last_data_from. Once the packet is done that reference goes away and the transport is freed by RCU, so the next delayed SACK carries the pointer into the SACK chunk and sctp_outq_select_transport() reads the freed transport's state. Drop the chunk in sctp_inq_push(), next to the existing rcvr->dead check. Both paths reach it with the association's socket lock held. The peer retransmits it. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim Acked-by: Xin Long Link: https://patch.msgid.link/aoUJHQmxL0LFIMCw@v4bel Signed-off-by: Jakub Kicinski

sctp: fix missing encap_port propagation for GSO fragments

2026-04-13T23:49:37+00:00

encap_port in SCTP_INPUT_CB(skb) is used by sctp_vtag_verify() for SCTP-over-UDP processing. In the GSO case, it is only set on the head skb, while fragment skbs leave it 0. This results in fragment skbs seeing encap_port == 0, breaking SCTP-over-UDP connections. Fix it by propagating encap_port from the head skb cb when initializing fragment skbs in sctp_inq_pop(). Fixes: 046c052b475e ("sctp: enable udp tunneling socks") Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/ea65ed61b3598d8b4940f0170b9aa1762307e6c3.1776017631.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski

sctp: avoid NULL dereference when chunk data buffer is missing

2025-10-23T02:19:31+00:00

chunk->skb pointer is dereferenced in the if-block where it's supposed to be NULL only. chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list instead and do it just before replacing chunk->skb. We're sure that otherwise chunk->skb is non-NULL because of outer if() condition. Fixes: 90017accff61 ("sctp: Add GSO support") Signed-off-by: Alexey Simakov Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/20251021130034.6333-1-bigalex934@gmail.com Signed-off-by: Jakub Kicinski

net: sctp: fix skb leak in sctp_inq_free()

2024-02-15T15:34:52+00:00

In case of GSO, 'chunk->skb' pointer may point to an entry from fraglist created in 'sctp_packet_gso_append()'. To avoid freeing random fraglist entry (and so undefined behavior and/or memory leak), introduce 'sctp_inq_chunk_free()' helper to ensure that 'chunk->skb' is set to 'chunk->head_skb' (i.e. fraglist head) before calling 'sctp_chunk_free()', and use the aforementioned helper in 'sctp_inq_pop()' as well. Reported-by: syzbot+8bb053b5d63595ab47db@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?id=0d8351bbe54fd04a492c2daab0164138db008042 Fixes: 90017accff61 ("sctp: Add GSO support") Suggested-by: Xin Long Signed-off-by: Dmitry Antipov Acked-by: Xin Long Link: https://lore.kernel.org/r/20240214082224.10168-1-dmantipov@yandex.ru Signed-off-by: Jakub Kicinski

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 104

2019-05-24T15:39:00+00:00

Based on 1 normalized pattern(s): this sctp implementation is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 or at your option any later version this sctp implementation is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with gnu cc see the file copying if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 42 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Kate Stewart Reviewed-by: Richard Fontana Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190523091649.683323110@linutronix.de Signed-off-by: Greg Kroah-Hartman

sctp: fix the issue that the cookie-ack with auth can't get processed

2018-05-02T15:15:33+00:00

When auth is enabled for cookie-ack chunk, in sctp_inq_pop, sctp processes auth chunk first, then continues to the next chunk in this packet if chunk_end + chunk_hdr size < skb_tail_pointer(). Otherwise, it will go to the next packet or discard this chunk. However, it missed the fact that cookie-ack chunk's size is equal to chunk_hdr size, which couldn't match that check, and thus this chunk would not get processed. This patch fixes it by changing the check to chunk_end + chunk_hdr size <= skb_tail_pointer(). Fixes: 26b87c788100 ("net: sctp: fix remote memory pressure from excessive queueing") Signed-off-by: Xin Long Acked-by: Neil Horman Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

net: use skb_is_gso_sctp() instead of open-coding

2018-03-09T16:41:47+00:00

As well as the basic conversion, I noticed that a lot of the SCTP code checks gso_type without first checking skb_is_gso() so I have added that where appropriate. Also, document the helper. Cc: Daniel Borkmann Cc: Marcelo Ricardo Leitner Signed-off-by: Daniel Axtens Signed-off-by: David S. Miller

sctp: remove the typedef sctp_chunkhdr_t

2017-07-01T16:08:41+00:00

This patch is to remove the typedef sctp_chunkhdr_t, and replace with struct sctp_chunkhdr in the places where it's using this typedef. It is also to fix some indents and use sizeof(variable) instead of sizeof(type)., especially in sctp_new. Signed-off-by: Xin Long Signed-off-by: David S. Miller

sctp: rename WORD_TRUNC/ROUND macros

2016-09-22T07:13:26+00:00

To something more meaningful these days, specially because this is working on packet headers or lengths and which are not tied to any CPU arch but to the protocol itself. So, WORD_TRUNC becomes SCTP_TRUNC4 and WORD_ROUND becomes SCTP_PAD4. Reported-by: David Laight Reported-by: David Miller Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller