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

sctp: validate STALE_COOKIE cause length before reading staleness

2026-07-24T14:21:07+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 addr_wq_timer race in sctp_free_addr_wq()

2026-07-24T14:20:35+00:00

[ Upstream commit 976c19de0f22a857ba0112f39635f8fd7a257568 ]

sctp_free_addr_wq() previously removed addr_wq_timer using timer_delete()
while holding addr_wq_lock. However, timer_delete() does not guarantee that
a currently running timer handler has completed.

This allows a race with sctp_addr_wq_timeout_handler(), where the handler
may still run after addr_waitq has been freed, acquire addr_wq_lock, and
access freed memory, leading to a use-after-free.

Fix this by calling timer_shutdown_sync() before taking addr_wq_lock.  This
guarantees that any in-flight timer handler has finished and prevents the
timer from being re-armed during teardown, making subsequent cleanup safe.

Fixes: 4db67e808640 ("sctp: Make the address lists per network namespace")
Reported-by: Sashiko 
Signed-off-by: Xin Long 
Link: https://patch.msgid.link/5dc95f295bdb5c3f60e880dd9aa5112dc5c071cc.1782757874.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

sctp: add INIT verification after cookie unpacking

2026-07-24T14:20:33+00:00

[ Upstream commit 414c5447fe6a200613dd46d7fdc8454622076cb1 ]

In SCTP handshake, the INIT chunk is initially processed by the server
and embedded into the cookie carried in INIT-ACK. The client then
returns this cookie via COOKIE-ECHO, where the server unpacks it and
reconstructs the original INIT chunk.

When cookie authentication is enabled, the cookie contents are protected
against tampering, so reusing the unpacked INIT without re-verification
is safe.

However, when cookie authentication is disabled, the reconstructed INIT
can no longer be trusted. In this case, the INIT must be explicitly
validated after unpacking to avoid processing potentially tampered data.

Add sctp_verify_init() checks after cookie unpacking in COOKIE-ECHO
processing paths (sctp_sf_do_5_1D_ce() and sctp_sf_do_5_2_4_dupcook())
when cookie_auth_enable is disabled. On failure, the new association is
freed and the packet is discarded.

Also tighten cookie validation in sctp_unpack_cookie() by verifying the
embedded chunk type is SCTP_CID_INIT before treating it as an INIT
chunk.

Finally, update sctp_verify_init() to validate parameter bounds using
the actual embedded INIT length instead of chunk->chunk_end, since the
INIT stored in COOKIE-ECHO may not span the entire chunk buffer.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long
Link: https://patch.msgid.link/ebcbbac574815b0850f371b4bdb02f2e602b94d3.1782341592.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski
Signed-off-by: Sasha Levin

sctp: fix SCTP_RESET_STREAMS stream list length limit

2026-07-24T14:20:32+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

udp_tunnel: Pass struct sock to setup_udp_tunnel_sock().

2026-07-24T14:20:31+00:00

[ Upstream commit 2cba193628fe523cee6dd61938db2c4563ce15a9 ]

None of the udp_tunnel users need struct socket in their
fast paths; it is only used for tunnel setup / teardown.

Even setup_udp_tunnel_sock() does not need struct socket.

Let's change setup_udp_tunnel_sock() to take struct sock
instead of struct socket.

Signed-off-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20260502031401.3557229-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski 
Stable-dep-of: c1481c94e74c ("tipc: avoid busy looping in tipc_exit_net()")
Signed-off-by: Sasha Levin

udp_tunnel: Pass struct sock to udp_tunnel_sock_release().

2026-07-24T14:20:31+00:00

[ Upstream commit 944bfc1b1c6fe9417668006aae7124886bcca038 ]

None of the udp_tunnel users need struct socket in their
fast paths; it is only used for tunnel setup / teardown.

While the UDP tunnel interface accepts struct socket, this
encourages users to store the pointer unnecessarily.  This
leads to extra dereferences when accessing struct sock fields
(e.g., sk->sk_user_data instead of sock->sk->sk_user_data).

Furthermore, these dereferences necessitate synchronize_rcu()
in udp_tunnel_sock_release() to protect the fast paths from
sock_orphan() setting sk->sk_socket to NULL.

This overhead can be avoided if users store the struct sock
pointer directly in their private structures.

As a prep, let's change udp_tunnel_sock_release() to take
struct sock instead of struct socket.

Signed-off-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20260502031401.3557229-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski 
Stable-dep-of: c1481c94e74c ("tipc: avoid busy looping in tipc_exit_net()")
Signed-off-by: Sasha Levin

sctp: fix err_chunk memory leaks in INIT handling

2026-07-24T14:20:28+00:00

[ Upstream commit 9f58a0a4d6c2ed5d341bba64f058f15d1b0c36f2 ]

When sctp_verify_init() encounters unrecognized parameters, it allocates an
err_chunk to report them. However, this chunk is leaked in several code
paths:

1. In sctp_sf_do_5_1B_init(), if security_sctp_assoc_request() fails after
   sctp_verify_init() has populated err_chunk, the function returns
   immediately without freeing it.

2. In sctp_sf_do_unexpected_init(), the same leak occurs on the
   security_sctp_assoc_request() failure path.

3. In sctp_sf_do_unexpected_init(), on the success path after copying
   unrecognized parameters to the INIT-ACK, the function returns without
   freeing err_chunk, unlike sctp_sf_do_5_1B_init() which properly frees
   it.

Fix all three leaks by adding sctp_chunk_free(err_chunk) calls before
returning in the error paths and on the success path in
sctp_sf_do_unexpected_init().

Fixes: c081d53f97a1 ("security: pass asoc to sctp_assoc_request and sctp_sk_clone")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Sashiko 
Signed-off-by: Xin Long 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/0656704f1b0158287c98aec09ba36c83e4a537ab.1781970534.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

sctp: hold socket lock when dumping endpoints in sctp_diag

2026-07-24T14:20:18+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

2026-07-24T14:19:49+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: validate embedded INIT chunk and address list lengths in cookie

2026-06-10T01:16:51+00:00

sctp_unpack_cookie() only checked that the embedded INIT chunk length
did not exceed the remaining cookie payload, but did not ensure that the
INIT chunk is large enough to contain a complete INIT header.

A malformed COOKIE_ECHO can therefore carry a truncated INIT chunk whose
length field is smaller than sizeof(struct sctp_init_chunk).  Later,
sctp_process_init() accesses INIT parameters unconditionally, which may
lead to out-of-bounds reads.

In addition, raw_addr_list_len is not fully validated against the
remaining cookie payload. When cookie authentication is disabled, an
attacker can supply an oversized raw_addr_list_len and cause
sctp_raw_to_bind_addrs() to read beyond the end of the cookie. The
address parser also lacks sufficient bounds checks for parameter headers
and lengths, allowing malformed address parameters to trigger
out-of-bounds reads.

Fix this by:

- requiring the embedded INIT chunk length to be at least sizeof(struct
  sctp_init_chunk);
- validating that the INIT chunk and raw address list together fit
  within the cookie payload;
- verifying sufficient data exists for each address parameter header and
  payload before parsing it.

Note that sctp_verify_init() must be called after sctp_unpack_cookie()
and before sctp_process_init() when cookie authentication is disabled.
This will be addressed in a separate patch.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Sashiko 
Signed-off-by: Xin Long 
Link: https://patch.msgid.link/75af23a89adf881a0895d511775e4770da367cbf.1780873427.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski