kernel/git/stable/linux.git/net/sctp, branch linux-rolling-stable

sctp: fix stream->outcnt underflow on duplicate RECONF responses

2026-09-07T15:37:10+00:00

commit 3faf13aff243ca9f78d08b1a2956ef5a6fc77b6e upstream. A cached RECONF chunk may contain more than one request parameter. A duplicate response can therefore find and process the same ADD_OUT request again while another parameter is still outstanding, rolling back outcnt twice and possibly underflowing it. Track outstanding request types as bits and clear each bit after its first response. Later responses for the same request are then ignored. Fixes: 11ae76e67a17 ("sctp: implement receiver-side procedures for the Reconf Response Parameter") Cc: stable@kernel.org Reported-by: TencentOS Corvus AI Link: https://lore.kernel.org/netdev/20260730110225.37371-1-juny24602@gmail.com/ Suggested-by: Xin Long Assisted-by: tencentos-corvus-ai:kimi-k3 Signed-off-by: Jun Yang Link: https://patch.msgid.link/20260824081832.98717-3-juny24602@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

sctp: distinguish sequence zero from wildcard in reconf lookup

2026-09-07T15:37:10+00:00

commit 63f44178f0a0f86060c9b576d6efab8a3ffa403e upstream. Zero is a valid response sequence after strreset_outseq wraps, but sctp_chunk_lookup_strreset_param() currently treats it as a wildcard. Add match_seq so response lookups match zero exactly while the one type-only lookup can still ignore the sequence. Fixes: 50a41591f110 ("sctp: implement receiver-side procedures for the Add Outgoing Streams Request Parameter") Cc: stable@kernel.org Suggested-by: Simon Horman Acked-by: Xin Long Signed-off-by: Jun Yang Link: https://patch.msgid.link/20260824081832.98717-2-juny24602@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

sctp: fix NULL deref on untransmitted RECONF completion

2026-09-07T15:37:10+00:00

commit 2db9bfa3e27bdea15e05ea70b56bad3d21e570ec upstream. sctp_process_strreset_outreq(), sctp_process_strreset_addstrm_out() and sctp_process_strreset_resp() complete a pending stream reconfiguration request by stopping the reconf timer on the transport it was sent on: t = asoc->strreset_chunk->transport; if (timer_delete(&t->reconf_timer)) sctp_transport_put(t); chunk->transport is assigned by __sctp_packet_append_chunk() when the chunk is appended to an outbound packet, and sctp_outq_flush_ctrl() arms the reconf timer at that same point. A request already published in asoc->strreset_chunk but not yet transmitted has neither, so completing it dereferences NULL. Two ways to get there. sctp_send_asconf_del_ip() sets asoc->src_out_of_asoc_ok without sending anything when the address being removed is the association's last one, and sctp_outq_flush_ctrl() then leaves every non-ASCONF control chunk queued; as only sctp_process_asconf_ack() clears that flag, it persists. An unprivileged process that removes such an address and then asks for a stream reset panics the kernel from softirq. A peer needs neither ASCONF nor local help: sctp_cmd_interpreter() uncorks the outqueue only once the whole packet has been processed, so a reply built while walking a RECONF chunk stays untransmitted for the rest of that walk, and one RECONF chunk carrying [Incoming SSN Reset Request, Outgoing SSN Reset Request, Response] -- or two RECONF chunks in one packet -- reaches the same dereference. KASAN: null-ptr-deref in range [0x00000000000001e8-0x00000000000001ef] RIP: 0010:timer_delete+0x67/0x110 Call Trace: sctp_process_strreset_addstrm_out (net/sctp/stream.c:832) sctp_sf_do_reconf (net/sctp/sm_statefuns.c:4212) sctp_do_sm (net/sctp/sm_sideeffect.c:1172) sctp_assoc_bh_rcv (net/sctp/associola.c:1044) sctp_rcv (net/sctp/input.c:243) ip_local_deliver (net/ipv4/ip_input.c:262) process_backlog (net/core/dev.c:6680) A response can only acknowledge a request that was actually sent, so do not match asoc->strreset_chunk while chunk->transport is NULL. Guarding the lookup covers all three completion sites. Fixes: 810544764536 ("sctp: implement receiver-side procedures for the Outgoing SSN Reset Request Parameter") Cc: stable@vger.kernel.org Reported-by: Xiang Mei Suggested-by: Xin Long Assisted-by: Claude:claude-opus-5 Signed-off-by: Weiming Shi Acked-by: Xin Long Link: https://patch.msgid.link/20260823172857.896146-2-bestswngs@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

sctp: drop a chunk if its transport was removed

2026-09-07T15:37:10+00:00

commit 03a9d10ecf71f54b2af8020935f2033d4a132be5 upstream. 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 Signed-off-by: Greg Kroah-Hartman

sctp: stop processing a packet once its association is deleted

2026-09-07T15:37:10+00:00

commit 47e15a8d12e366d0d261bcbc394394f44418938d upstream. sctp_endpoint_bh_rcv() looks the association up only when chunk->asoc is NULL, and caches the result in chunk->asoc and chunk->transport without taking a reference. A packet that matches no association is handed to the endpoint, so a peer can bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The COOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and with the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(), so the association and its transports are freed. The endpoint loop has no counterpart to the asoc->base.dead check in sctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed transport and is then passed to sctp_do_sm() with the freed association. The transport is freed through RCU, so this needs the packet to come off the socket backlog, where the loop runs in task context. The endpoint loop cannot do the same check: it holds no reference on the association, so reading asoc->base.dead would itself be a use-after-free. Mark the packet for discard in the command interpreter, just before it deletes the association. That is also before sctp_inq_free() releases the chunk on the association receive path. sctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary association, while the one the packet belongs to stays alive. A restarting peer can bundle DATA behind its COOKIE ECHO, so compare against chunk->asoc and leave that case alone. 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/an-YYtoqw1QpTXUL@v4bel Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sctp: fix use-after-free of cached ASCONF chunk

2026-08-13T00:54:42+00:00

addip_last_asconf caches the outstanding outbound ASCONF chunk. The normal ASCONF-ACK completion path releases the chunk and clears the pointer. However, sctp_asconf_queue_teardown() releases the cached chunk without clearing addip_last_asconf. During peer restart handling, sctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes sctp_asconf_queue_teardown() while the association remains alive and leaves the pointer dangling. A delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(), which accesses the stale chunk and passes it to sctp_process_asconf_ack(), causing a use-after-free and a second release. Clearing the pointer exposes a race with T4 expiry. Peer restart handling queues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses timer_delete(), which does not wait for a callback already running on another CPU. Such a callback can reach sctp_sf_t4_timer_expire() after the purge and dereference NULL. Clear addip_last_asconf after releasing the cached chunk, and make sctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding ASCONF remains. Fixes: a000c01e60e4 ("sctp: stop pending timers and purge queues when peer restart asoc") Cc: stable@vger.kernel.org Suggested-by: Xin Long Signed-off-by: Yuxiang Yang Acked-by: Xin Long Link: https://patch.msgid.link/20260809043806.2768302-1-yangyx22@mails.tsinghua.edu.cn Signed-off-by: Jakub Kicinski

sctp: clear new_transport when removing a peer

2026-08-13T00:21:37+00:00

sctp_process_asconf_param() stores a newly added peer transport in asoc->new_transport. After all parameters in the ASCONF chunk have been processed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the new transport. An authenticated ASCONF from a remote SCTP peer can add a transport and remove it again with a wildcard DEL-IP parameter in the same chunk. The wildcard deletion preserves the transport on which the ASCONF arrived, but removes the newly added transport through sctp_assoc_del_nonprimary_peers(). The removal does not clear asoc->new_transport, leaving it pointing to the removed transport. sctp_sf_do_asconf() then creates a HEARTBEAT whose chunk->transport points to the removed transport without holding a transport reference. During local address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on control_chunk_list. After the transport is freed by RCU, a successful ASCONF_ACK for the replacement address releases the queued HEARTBEAT and sctp_outq_select_transport() reads the freed transport's state. The issue was found during a static audit of SCTP objects. With an authenticated peer, the reproducer triggered the same KASAN report in 2 of 2 unpatched runs on a KASAN-enabled netdev/main kernel: BUG: KASAN: slab-use-after-free in sctp_outq_select_transport Read of size 4 at addr ffff88800b9bd95c by task python3/197 Call Trace: sctp_outq_select_transport+0x549/0x8b0 [sctp] sctp_outq_flush+0x306/0x2c60 [sctp] sctp_transport_immediate_rtx+0xaf/0x260 [sctp] sctp_process_asconf_ack+0xa48/0xf70 [sctp] Allocated by task 197: sctp_transport_new+0x68/0x650 [sctp] sctp_assoc_add_peer+0x258/0x12a0 [sctp] sctp_process_asconf+0x5e9/0x1090 [sctp] Last potentially related work creation: __call_rcu_common.constprop.0+0x77/0xb70 sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp] sctp_process_asconf+0xd9c/0x1090 [sctp] The first invalid access was a four-byte read of transport->state at net/sctp/outqueue.c:833. The same reproducer completed the full authenticated ASCONF and local-address replacement sequence with this change without a KASAN report or oops. Clear new_transport when its peer is removed, before it can be used to create the HEARTBEAT. Fixes: 6af29ccc223b ("sctp: Bundle HEAERTBEAT into ASCONF_ACK") Cc: stable@vger.kernel.org Signed-off-by: Qing Ming Acked-by: Xin Long Link: https://patch.msgid.link/20260811152803.5629-1-a0yami@mailbox.org Signed-off-by: Jakub Kicinski

sctp: validate cookie AUTH state before use

2026-08-07T22:02:32+00:00

When cookie authentication is disabled, COOKIE_ECHO restores fixed-size AUTH fields directly from peer-controlled cookie bytes. A forged RANDOM length, HMAC list, or CHUNKS list can then reach association consumers with lengths or identifiers that were never validated against the local backing arrays. A forged RANDOM length can cause out-of-bounds reads during key-vector construction. A forged HMAC identifier also caused a 32-byte write past a zero-length AUTH chunk, providing a primitive for a local privilege escalation chain. Validate the cookie's RANDOM, HMACS, and CHUNKS parameters at the cookie trust boundary before copying them into the association. Reject invalid types, malformed lengths, unsupported HMAC identifiers, HMAC lists without SHA1, and forbidden chunk ids. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Fixes: 1f485649f529 ("[SCTP]: Implement SCTP-AUTH internals") Signed-off-by: Jérémy Jean Acked-by: Xin Long Link: https://patch.msgid.link/20260804200042.2412009-1-Jeremy.Jean@oss.cyber.gouv.fr Signed-off-by: Jakub Kicinski

sctp: clear control chunk transport if it is being removed

2026-08-06T16:29:47+00:00

sctp_make_heartbeat_ack() caches the destination transport in chunk->transport without taking a reference. When src_out_of_asoc_ok is enabled, the HEARTBEAT ACK may remain queued on control_chunk_list instead of being transmitted immediately. If the peer transport is removed while the chunk is still queued, sctp_assoc_rm_peer() drops the transport and schedules it for RCU freeing, but only clears cached transport pointers in out_chunk_list. The queued control chunk therefore retains a dangling transport pointer. Once an ASCONF_ACK clears the suppression and the queued control chunk is transmitted, SCTP dereferences the stale transport pointer, leading to a use-after-free. Fix this by also clearing chunk->transport for queued control chunks in control_chunk_list when removing the transport. Fixes: 8a07eb0a50ae ("sctp: Add ASCONF operation on the single-homed host") Reported-by: Daniele Linguaglossa Signed-off-by: Xin Long Link: https://patch.msgid.link/7e1168cb722132152a29d47e5eafaeac4a3bf6f3.1785943120.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski

sctp: fix addip_serial increment on ASCONF_ACK allocation failure

2026-08-05T03:06:39+00:00

In sctp_process_asconf(), when sctp_make_asconf_ack() fails to allocate the ASCONF_ACK chunk due to memory pressure, the code jumps to the done label where asoc->peer.addip_serial is unconditionally incremented. This leaves the peer's ASCONF (serial N) unacknowledged while the local endpoint now expects serial N+1. When the peer retransmits serial N, it falls into the serial < addip_serial + 1 branch , which attempts to look up a cached ACK for serial N. No cached ACK exists since the allocation failed, so the retransmission is silently discarded. The peer eventually times out and ABORTs the association. Move the addip_serial increment inside the if (asconf_ack) block so that the serial number is only advanced when the ASCONF_ACK is successfully created and cached. This way, on allocation failure, the serial number is unchanged and the peer's retransmitted ASCONF will be correctly re-processed. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Qing Luo Acked-by: Xin Long Link: https://patch.msgid.link/20260804025514.241767-1-l1138897701@163.com Signed-off-by: Jakub Kicinski