linux-stable.git/net/sctp/stream.c, branch linux-rolling-lts

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

2026-09-07T15:22:46+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

2026-09-07T15:22:46+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

2026-09-07T15:22:46+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: 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: stream: fully roll back denied add-stream state

2026-06-19T11:44:11+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

treewide: Switch/rename to timer_delete[_sync]()

2025-04-05T08:30:12+00:00

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.

Conversion was done with coccinelle plus manual fixups where necessary.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar

sctp: Fix undefined behavior in left shift operation

2025-02-20T02:55:40+00:00

According to the C11 standard (ISO/IEC 9899:2011, 6.5.7):
"If E1 has a signed type and E1 x 2^E2 is not representable in the result
type, the behavior is undefined."

Shifting 1 << 31 causes signed integer overflow, which leads to undefined
behavior.

Fix this by explicitly using '1U << 31' to ensure the shift operates on
an unsigned type, avoiding undefined behavior.

Signed-off-by: Yu-Chun Lin 
Link: https://patch.msgid.link/20250218081217.3468369-1-eleanor15x@gmail.com
Signed-off-by: Jakub Kicinski

sctp: delete the nested flexible array params

2023-04-21T07:19:29+00:00

This patch deletes the flexible-array params[] from the structure
sctp_inithdr, sctp_addiphdr and sctp_reconf_chunk to avoid some
sparse warnings:

  # make C=2 CF="-Wflexible-array-nested" M=./net/sctp/
  net/sctp/input.c: note: in included file (through include/net/sctp/structs.h, include/net/sctp/sctp.h):
  ./include/linux/sctp.h:278:29: warning: nested flexible array
  ./include/linux/sctp.h:675:30: warning: nested flexible array

This warning is reported if a structure having a flexible array
member is included by other structures.

Signed-off-by: Xin Long 
Signed-off-by: David S. Miller

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

sctp: leave the err path free in sctp_stream_init to sctp_stream_free

2022-07-28T01:23:22+00:00

A NULL pointer dereference was reported by Wei Chen:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  RIP: 0010:__list_del_entry_valid+0x26/0x80
  Call Trace:
   
   sctp_sched_dequeue_common+0x1c/0x90
   sctp_sched_prio_dequeue+0x67/0x80
   __sctp_outq_teardown+0x299/0x380
   sctp_outq_free+0x15/0x20
   sctp_association_free+0xc3/0x440
   sctp_do_sm+0x1ca7/0x2210
   sctp_assoc_bh_rcv+0x1f6/0x340

This happens when calling sctp_sendmsg without connecting to server first.
In this case, a data chunk already queues up in send queue of client side
when processing the INIT_ACK from server in sctp_process_init() where it
calls sctp_stream_init() to alloc stream_in. If it fails to alloc stream_in
all stream_out will be freed in sctp_stream_init's err path. Then in the
asoc freeing it will crash when dequeuing this data chunk as stream_out
is missing.

As we can't free stream out before dequeuing all data from send queue, and
this patch is to fix it by moving the err path stream_out/in freeing in
sctp_stream_init() to sctp_stream_free() which is eventually called when
freeing the asoc in sctp_association_free(). This fix also makes the code
in sctp_process_init() more clear.

Note that in sctp_association_init() when it fails in sctp_stream_init(),
sctp_association_free() will not be called, and in that case it should
go to 'stream_free' err path to free stream instead of 'fail_init'.

Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
Reported-by: Wei Chen 
Signed-off-by: Xin Long 
Link: https://lore.kernel.org/r/831a3dc100c4908ff76e5bcc363be97f2778bc0b.1658787066.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski