kernel/linux.git/net/sctp, branch v6.12.97

sctp: validate STALE_COOKIE cause length before reading staleness

2026-07-24T14:11:37+00:00

commit 1cd23ca80784223fa2204e16203f754da4e821f8 upstream. When an ERROR chunk with a STALE_COOKIE cause is received in the COOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure of Staleness that follows the cause header: err = (struct sctp_errhdr *)(chunk->skb->data); stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err))); err is the first cause in the chunk, not the STALE_COOKIE cause that caused the dispatch, and nothing guarantees the staleness field is present. sctp_walk_errors() only requires a cause to be as long as the 4-byte header, so for a STALE_COOKIE cause of length 4 the read runs past the cause, and for a minimal ERROR chunk past skb->tail. The value is echoed to the peer in the Cookie Preservative of the reply INIT, leaking uninitialized memory. sctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so check its length there and pass it to sctp_sf_do_5_2_6_stale(), which reads that cause instead of the first one. A STALE_COOKIE cause too short to hold the staleness field is discarded. The read is reachable by any peer that can drive an association into COOKIE_ECHOED, including an unprivileged process using a raw SCTP socket in a user and network namespace. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Cc: stable@vger.kernel.org Signed-off-by: Weiming Shi Acked-by: Xin Long Link: https://patch.msgid.link/20260704033545.2438373-2-bestswngs@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

sctp: fix SCTP_RESET_STREAMS stream list length limit

2026-07-24T14:11:18+00:00

[ Upstream commit 2b9f5ef534184bd81b8a4772780626c40eed1fd5 ] SCTP_RESET_STREAMS carries a flexible array of u16 stream IDs, but the optlen clamps treat USHRT_MAX as a byte count and then multiply sizeof(__u16) by the fixed header size. That caps the copied and validated option buffer at about 64 KiB, which rejects valid requests containing more than about half of the u16 stream ID range. Use struct_size_t() for the maximum struct sctp_reset_streams layout instead, so the bound matches the flexible array described by srs_number_streams. Fixes: 5960cefab9df ("sctp: add a ceiling to optlen in some sockopts") Acked-by: Xin Long Signed-off-by: Yousef Alhouseen Link: https://patch.msgid.link/20260625142354.2600-1-alhouseenyousef@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: hold socket lock when dumping endpoints in sctp_diag

2026-07-24T14:11:11+00:00

[ Upstream commit 7d8297e26b4e20b5d1c3c3fe51fe81a1c7fbc823 ] SCTP_DIAG endpoint dumping was traversing endpoint address lists without holding lock_sock(), while those lists could change concurrently via socket operations (e.g., bindx changes). This creates a race where nla_reserve() counts addresses under RCU protection, but the subsequent copy may see fewer entries, potentially leaking uninitialized memory to userspace. Fix this by: - Taking a reference on each endpoint during hash traversal - Moving socket operations (lock_sock()) outside read_lock_bh() - Serializing address list access during dump - Reworking sctp_for_each_endpoint() to support restart-based traversal with (net, pos) tracking Also: - Add WARN_ON_ONCE() for inconsistent address counts - Fix idiag_states filtering for LISTEN vs association cases - Skip dumping endpoints being freed (ep->base.dead) - Move dump position tracking into iterator, removing cb->args[4] and its comment for sctp_ep_dump()., - Update the comment for cb->args[4] and remove the comment for unused cb->args[5] for sctp_sock_dump(). Note: traversal is restart-based and may re-scan buckets multiple times, but this is acceptable due to small bucket sizes and required to support sleeping-safe callbacks. This issue was reported by Nico Yip (@_cyeaa_) working with TrendAI Zero Day Initiative. Reported-by: Zero Day Initiative Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Xin Long Link: https://patch.msgid.link/4c1b49ab87e0f7d552ebd8172b364b1994e913c9.1781552190.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: validate embedded address parameter length

2026-07-24T14:11:00+00:00

[ Upstream commit e9361d0ca55c4af12aac09e2572852fa91046229 ] sctp_verify_asconf() and sctp_verify_param() only validate ADD_IP, DEL_IP, and SET_PRIMARY parameters against a fixed minimum size of sizeof(struct sctp_addip_param) + sizeof(struct sctp_paramhdr). This ensures the outer parameter is large enough to contain an embedded address parameter header, but does not verify that the embedded address parameter's declared length fits within the bounds of the outer parameter. Later, sctp_process_param() and sctp_process_asconf_param() extract the embedded address parameter and pass it to af->from_addr_param(), which uses the address parameter length to parse the variable-length address payload. A malformed peer can therefore advertise an embedded address parameter length that exceeds the remaining bytes in the enclosing parameter. Validate that addr_param->p.length does not exceed the space available after the sctp_addip_param header before processing the embedded address parameter. Reject malformed parameters when the embedded address length extends beyond the enclosing parameter bounds. This prevents out-of-bounds reads when parsing malformed parameters carried in INIT or ASCONF processing paths. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: sashiko Signed-off-by: Xin Long Link: https://patch.msgid.link/7838b86b69f52add28808fb59034c8f992e97b2d.1781043268.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: disable BH before calling udp_tunnel_xmit_skb()

2026-07-04T11:43:28+00:00

commit 2cd7e6971fc2787408ceef17906ea152791448cf upstream. udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with BH disabled. After commit 6f1a9140ecda ("add xmit recursion limit to tunnel xmit functions"), on the path: udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit() dev_xmit_recursion_inc()/dec() must stay balanced on the same CPU. Without local_bh_disable(), the context may move between CPUs, which can break the inc/dec pairing. This may lead to incorrect recursion level detection and cause packets to be dropped in ip(6)_tunnel_xmit() or __dev_queue_xmit(). Fix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths. In my testing, after enabling the SCTP over UDP: # ip net exec ha sysctl -w net.sctp.udp_port=9899 # ip net exec ha sysctl -w net.sctp.encap_port=9899 # ip net exec hb sysctl -w net.sctp.udp_port=9899 # ip net exec hb sysctl -w net.sctp.encap_port=9899 # ip net exec ha iperf3 -s - without this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 37.2 MBytes 31.2 Mbits/sec sender [ 5] 0.00-10.00 sec 37.1 MBytes 31.1 Mbits/sec receiver - with this patch: # ip net exec hb iperf3 -c 192.168.0.1 --sctp [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec sender [ 5] 0.00-10.00 sec 3.14 GBytes 2.69 Gbits/sec receiver Fixes: 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions") Fixes: 046c052b475e ("sctp: enable udp tunneling socks") Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Link: https://patch.msgid.link/c874a8548221dcd56ff03c65ba75a74e6cf99119.1776017727.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Alexander Martyniuk Signed-off-by: Greg Kroah-Hartman

net: ipv6: Make udp_tunnel6_xmit_skb() void

2026-07-04T11:43:28+00:00

commit 6a7d88ca15f73c5c570c372238f71d63da1fda55 upstream. The function always returns zero, thus the return value does not carry any signal. Just make it void. Most callers already ignore the return value. However: - Refold arguments of the call from sctp_v6_xmit() so that they fit into the 80-column limit. - tipc_udp_xmit() initializes err from the return value, but that should already be always zero at that point. So there's no practical change, but elision of the assignment prompts a couple more tweaks to clean up the function. Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/7facacf9d8ca3ca9391a4aee88160913671b868d.1750113335.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Alexander Martyniuk Signed-off-by: Greg Kroah-Hartman

sctp: stream: fully roll back denied add-stream state

2026-06-19T11:42:34+00:00

commit a5f8a90ac9f77c678a9781c0a464b635e0d63e49 upstream. When ADD_OUT_STREAMS is denied, SCTP only shrinks the queued chunks and then lowers outcnt. That leaves removed stream metadata behind, so a later re-add can reuse a stale ext and hit a null-pointer dereference in the scheduler get path. Fix the rollback by tearing down the removed stream state the same way other stream resizes do. Unschedule the current scheduler state, drop the removed stream ext state with sctp_stream_outq_migrate(), and then reschedule the remaining streams. This keeps scheduler-private RR/FC/PRIO lists consistent while fully rolling back denied outgoing stream additions. Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Signed-off-by: Wyatt Feng Signed-off-by: Ren Wei Acked-by: Xin Long Link: https://patch.msgid.link/d78954ecd94954653ee299400e98d74a03a6f7d3.1780603399.git.bronzed_45_vested@icloud.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: diag: reject stale associations in dump_one path

2026-06-19T11:42:34+00:00

commit 5eba3e48d78edd7551b992cb7ba687019b3a78da upstream. The SCTP exact sock_diag lookup can hold a transport reference, block on lock_sock(sk), and then resume after sctp_association_free() has marked the association dead and freed its bind address list. When that happens, inet_assoc_attr_size() and inet_diag_msg_sctpasoc_fill() can still dereference association state that is no longer valid for reporting. In particular, inet_diag_msg_sctpasoc_fill() may read an empty bind-address list as a real sctp_sockaddr_entry and trigger an out-of-bounds read from unrelated association memory. Reject the association after taking the socket lock if it has been reaped or detached from the endpoint, and report the lookup as stale. This keeps the exact dump-one path from formatting torn association state. Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Signed-off-by: Zhao Zhang Signed-off-by: Ren Wei Acked-by: Xin Long Link: https://patch.msgid.link/fac6043fa20a2ff68e12958c431836f692c51268.1780113823.git.zzhan461@ucr.edu Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: fix uninit-value in __sctp_rcv_asconf_lookup()

2026-06-19T11:42:25+00:00

[ Upstream commit f8373d7090b745728de66308deeecc67e8d319ce ] __sctp_rcv_asconf_lookup() in net/sctp/input.c only checks that the ASCONF chunk can hold the ADDIP header and a parameter header, then calls af->from_addr_param(), which reads the full address (16 bytes for IPv6) trusting the parameter's declared length. An unauthenticated peer can send a truncated trailing ASCONF chunk that declares an IPv6 address parameter but stops after the 4-byte parameter header; reached from the no-association lookup path, from_addr_param() then reads uninitialized bytes past the parameter. Impact: an unauthenticated SCTP peer makes the receive path read up to 16 bytes of uninitialized memory past a truncated ASCONF address parameter. The sibling __sctp_rcv_init_lookup() bounds parameters with sctp_walk_params(); this path open-codes the fetch and omits the bound. Verify the whole address parameter lies within the chunk before from_addr_param() reads it, the same class of fix as commit 51e5ad549c43 ("net: sctp: fix KMSAN uninit-value in sctp_inq_pop"). Fixes: df2185771439 ("[SCTP]: Update association lookup to look at ASCONF chunks as well") Signed-off-by: Michael Bommarito Acked-by: Xin Long Link: https://patch.msgid.link/20260608122234.459098-1-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: purge outqueue on stale COOKIE-ECHO handling

2026-06-19T11:42:22+00:00

[ Upstream commit e374b22e9b07b72a25909621464ff74096151bfb ] sctp_stream_update() is only invoked when the association is moved into COOKIE_WAIT during association setup/reconfiguration. In this path, the outbound stream scheduler state (stream->out_curr) is expected to be clean, since no user data should have been transmitted yet unless the state machine has already partially progressed. However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a Stale Cookie ERROR is received, the association is rolled back from COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already have been queued and even bundled with the COOKIE-ECHO chunk. During the rollback, sctp_stream_update() frees the old stream table and installs a new one, but it does not invalidate stream->out_curr. As a result, out_curr may still point to a freed sctp_stream_out entry from the previous stream state. Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on stream->out_curr->ext, which can lead to use-after-free once the old stream state has been released via sctp_stream_free(). This results in crashes such as (reported by Yuqi): BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140 Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312 CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted 7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full) sctp_sched_fcfs_dequeue+0x13a/0x140 sctp_outq_flush+0x1603/0x33e0 sctp_do_sm+0x31c9/0x5d30 sctp_assoc_bh_rcv+0x392/0x6f0 sctp_inq_push+0x1db/0x270 sctp_rcv+0x138d/0x3c10 Fix this by fully purging the association outqueue when handling the Stale Cookie case. This ensures all pending transmit and retransmit state is dropped, and any scheduler cached pointers are invalidated, making it safe to rebuild stream state during COOKIE_WAIT restart. Updating only stream->out_curr would be insufficient, since queued and retransmittable data would still reference the old stream state and trigger later use-after-free in dequeue paths. Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Reported-by: Yuqi Xu Reported-by: Ren Wei Signed-off-by: Xin Long Link: https://patch.msgid.link/94318159b9052907a6cbb7256aee8b5f8dfbfccb.1780510304.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin