kernel/linux.git/net/sctp, branch v6.18.44

sctp: prevent peer transport count overflow

2026-08-09T18:25:18+00:00

commit bd0e9289e2642f6a5c54faad304ce0f41e926d22 upstream. sctp_assoc_add_peer() increments the association's 16-bit transport_count for every new unique peer. Adding the 65,536th transport wraps the count to zero. SCTP sock_diag uses transport_count to reserve the INET_DIAG_PEERS payload, then copies one sockaddr_storage for every entry in transport_addr_list. After the wrap, a diagnostic dump reserves an empty payload and writes 8 MiB of peer addresses past the skb tail. Reject a new unique peer when transport_count has reached U16_MAX. Perform the check after the existing-peer lookup so a duplicate address continues to return its existing transport at the limit. Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Cc: stable@vger.kernel.org Signed-off-by: Asim Viladi Oglu Manizada Acked-by: Xin Long Link: https://patch.msgid.link/20260725032053.521705-1-manizada@pm.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: reject stale cookies with mismatched verification tags

2026-08-09T18:25:18+00:00

commit 9d8da8e0a9bce4a340af60dd0446bc7eb8d07587 upstream. sctp_unpack_cookie() skips cookie expiration checks whenever an association already exists. This is broader than the exception in RFC 9260 Section 5.2.4. For an existing association, Section 5.2.4 permits an expired State Cookie only when both Verification Tags in the cookie match the current association. Otherwise, the packet SHOULD be discarded and a Stale Cookie ERROR MUST be sent. The broad check lets an expired Action A restart cookie reach sctp_sf_do_dupcook_a(). In a runtime test with the default 60 second cookie lifetime, replaying such a cookie after 65 seconds returned a COOKIE-ACK and restarted the association. Check cookie expiration unless both Verification Tags match. This preserves the Action D exception for a lost COOKIE ACK while rejecting expired cookies in all other cases. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Yuxiang Yang Acked-by: Xin Long Link: https://patch.msgid.link/20260723225623.2658868-1-yangyx22@mails.tsinghua.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: validate Adaptation Indication parameter length

2026-08-09T18:25:12+00:00

commit 74b21f52c5c5a71a05c0ff70e513f4f04ff28b17 upstream. The Adaptation Layer Indication parameter contains a fixed 32-bit Adaptation Code Point after its parameter header. However, sctp_verify_param() accepts a header-only parameter because the generic parameter walker only requires the header to be present. sctp_process_param() then reads adaptation_ind beyond the declared parameter. When the malformed parameter is last in an INIT, the read starts at the receive skb tail, and the value is copied into the state cookie returned in the INIT ACK. This may disclose four receive-buffer tail bytes. Require the declared parameter length to match the fixed structure size and abort the association through the existing invalid parameter length path otherwise. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Charles Vosburgh Acked-by: Xin Long Link: https://patch.msgid.link/20260727-sctp-adaptation-length-v1-1-0ab58b2810a5@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: close UDP tunnel sockets during netns teardown

2026-08-03T09:22:01+00:00

commit ffb2bd7ade36ec4da32c46a6eddbf4515316d08c upstream. proc_sctp_do_udp_port() starts per-net SCTP UDP tunneling sockets when net.sctp.udp_port is set, and stops/restarts them when the sysctl value changes. The netns exit path does not stop these sockets, so a namespace can be torn down while its SCTP UDP tunnel sockets are still installed. Close the UDP tunnel sockets from sctp_ctrlsock_exit() after unregistering the per-net sysctl table. This prevents new sysctl writes from racing in while the sockets are being released, and closes the sockets before the control socket is destroyed. Fixes: 046c052b475e ("sctp: enable udp tunneling socks") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/b9f1f02b0780ad6a719e2413f5f0bb8eb7702d94.1782585631.git.roxy520tt%40gmail.com Signed-off-by: Zhiling Zou Signed-off-by: Ren Wei Acked-by: Xin Long Link: https://patch.msgid.link/6dab75f22855cb219e2e30a5497cab03b970ab91.1784033357.git.roxy520tt@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: avoid auth_enable sysctl UAF during netns teardown

2026-08-03T09:22:01+00:00

commit f8d5e7846025f4ab15a461235f8ebae9094a361a upstream. proc_sctp_do_auth() updates the SCTP control socket after changing net.sctp.auth_enable. The handler gets the per-net SCTP state from ctl->data, so an already opened sysctl file can still target a network namespace while that namespace is being torn down. SCTP previously registered its per-net sysctls from sctp_defaults_init(), while the control socket is created later from sctp_ctrlsock_init(). This exposed a window during initialization where auth_enable was writable before net->sctp.ctl_sock existed, and a teardown window where auth_enable stayed writable after inet_ctl_sock_destroy() had released the control socket. Move the per-net SCTP sysctl registration into sctp_ctrlsock_init() after sctp_ctl_sock_init() succeeds, and unregister the sysctl table before destroying the control socket in sctp_ctrlsock_exit(). If sysctl registration fails after the control socket was created, destroy the control socket in the same init path. Make sctp_sysctl_net_unregister() tolerate a missing header and clear the saved pointer so init-error and exit paths can safely share the unregister helper. Fixes: 15649fd5415e ("sctp: sysctl: auth_enable: avoid using current->nsproxy") Cc: stable@vger.kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Co-developed-by: Qi Tang Signed-off-by: Qi Tang Signed-off-by: Zhiling Zou Signed-off-by: Ren Wei Acked-by: Xin Long Link: https://patch.msgid.link/390cd5e91ed60eea27b0b64d0468301a9e73b808.1784033357.git.roxy520tt@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: don't free the ASCONF's own transport in DEL-IP processing

2026-08-03T09:22:01+00:00

commit 9b2854f86f0b56e9027d68e7a3fc909d1a9b566f upstream. sctp_process_asconf() caches the transport the ASCONF chunk is processed against in asconf->transport (== chunk->transport, set once in sctp_rcv()). For an ASCONF located through its Address Parameter by __sctp_rcv_asconf_lookup(), that cached transport corresponds to the Address Parameter, which need not be the packet's source address. sctp_process_asconf_param() rejects a DEL-IP for the packet source address (ADDIP D8, SCTP_ERROR_DEL_SRC_IP), but nothing protects asconf->transport. A single ASCONF can therefore carry, in order: [Address Parameter L] [DEL-IP L] [DEL-IP 0.0.0.0] where L differs from the source. The DEL-IP for L passes the D8 check and calls sctp_assoc_rm_peer() on the transport that asconf->transport still points at, freeing it (RCU-deferred). The following wildcard DEL-IP then reuses the now-dangling asconf->transport in sctp_assoc_set_primary() and sctp_assoc_del_nonprimary_peers(): set_primary() dereferences the freed transport (->ipaddr, ->state) and plants the dangling pointer into asoc->peer.primary_path / active_path, and del_nonprimary_peers(), keeping only the pointer that is no longer on the list, removes every real transport, leaving the association with a transport_count of 0 and primary_path/active_path pointing at freed memory. Reject a DEL-IP that targets the transport the ASCONF is being processed against, mirroring the existing source-address guard, so the wildcard branch can never reuse a freed transport. Fixes: 42e30bf3463c ("[SCTP]: Handle the wildcard ADD-IP Address parameter") Cc: stable@kernel.org Signed-off-by: Jun Yang Acked-by: Xin Long Link: https://patch.msgid.link/tencent_73762ED1DF08CC9D5F5F61954B01350CFE0A@qq.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: auth: verify auth requirement when auth_chunk is NULL

2026-08-03T09:21:45+00:00

[ Upstream commit 8e04823c120b376ef7dab14b60ebf6823aa16c14 ] sctp_auth_chunk_verify() returns true unconditionally when chunk->auth_chunk is NULL, silently skipping authentication. This is incorrect when: 1. skb_clone() failed in the BH receive path, leaving auth_chunk NULL. In sctp_endpoint_bh_rcv() asoc is NULL for new connections, so the early sctp_auth_recv_cid() check cannot catch this. 2. No AUTH chunk precedes COOKIE-ECHO, so skb_clone() is never called and auth_chunk remains NULL. Fix by checking sctp_auth_recv_cid() when auth_chunk is NULL: if authentication is required, return false to drop the chunk; otherwise continue normally. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Signed-off-by: Qing Luo Acked-by: Xin Long Link: https://patch.msgid.link/20260721015532.120157-2-l1138897701@163.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: validate stream count in sctp_process_strreset_inreq()

2026-08-03T09:21:42+00:00

[ Upstream commit 18ae07691d43183d270de8be9dc8e027906015d9 ] When processing a RESET_IN_REQUEST from a peer, sctp_process_strreset_inreq() derives the stream count from the parameter length but does not check whether the resulting RESET_OUT_REQUEST would exceed SCTP_MAX_CHUNK_LEN. The OUT request header (sctp_strreset_outreq, 16 bytes) is 8 bytes larger than the IN request header (sctp_strreset_inreq, 8 bytes). Generally, the IP payload is bounded to 65535 bytes, so the stream list cannot be large enough to trigger the overflow. However, on interfaces with MTU > 65535 (e.g., loopback with IPv6 jumbograms), a stream list that fits within the incoming IN parameter can cause a __u16 overflow in sctp_make_strreset_req() when computing the OUT request size, leading to an undersized skb allocation and a kernel BUG: net/core/skbuff.c:207 skb_panic net/core/skbuff.c:2625 skb_put net/sctp/sm_make_chunk.c:1535 sctp_addto_chunk net/sctp/sm_make_chunk.c:3695 sctp_make_strreset_req net/sctp/stream.c:655 sctp_process_strreset_inreq The local setsockopt path validates the generated reset request size. However, for an incoming-only reset, it accounts for the smaller IN request even though the peer must generate an OUT request with the same stream list. Such a request cannot be completed successfully by the peer. Reject peer IN requests whose corresponding OUT request would exceed SCTP_MAX_CHUNK_LEN. Also tighten the local check so it does not send an IN request that would require an oversized OUT request from the peer. Fixes: 7f9d68ac944e ("sctp: implement sender-side procedures for SSN Reset Request Parameter") Reported-by: AutonomousCodeSecurity@microsoft.com Closes: https://lore.kernel.org/all/20260707203215.2752-1-blbllhy@gmail.com/ Suggested-by: Xin Long Signed-off-by: Cen Zhang (Microsoft) Acked-by: Xin Long Link: https://patch.msgid.link/20260710010718.20318-1-blbllhy@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: fix auth_chunk_list capacity check in sctp_auth_ep_add_chunkid

2026-08-03T09:21:42+00:00

[ Upstream commit ff04b26794a16a8a879eb4fd2c02c2d6b03850e9 ] sctp_auth_ep_add_chunkid() uses SCTP_NUM_CHUNK_TYPES (20) as the capacity limit for ep->auth_chunk_list, allowing it to hold up to 20 chunk entries (param_hdr.length up to 24). However, the copy destination asoc->c.auth_chunks in struct sctp_cookie is only SCTP_AUTH_MAX_CHUNKS (16) entries (20 bytes). When more than 16 chunks are added, sctp_association_init() memcpy overflows the destination by up to 4 bytes. Fix by using SCTP_AUTH_MAX_CHUNKS as the capacity limit, matching the destination capacity. Fixes: 1f485649f529 ("[SCTP]: Implement SCTP-AUTH internals") Signed-off-by: HanQuan Acked-by: Xin Long Link: https://patch.msgid.link/20260713032021.3491702-1-zhoujian.zja@antgroup.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

sctp: validate STALE_COOKIE cause length before reading staleness

2026-07-24T14:17:06+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