sctp_init_cause() accepts a chunk when skb_tailroom() can hold the
cause header and the payload. sctp_addto_chunk() then writes 0-3
bytes of padding before that header so the chunk stays 4-byte
aligned. The check does not include the padding, and the following
skb_put() calls skb_over_panic() from softirq.

Count the padding sctp_addto_chunk() is about to write. The cause
length on the wire stays the header plus the payload.

Found by LLM inspection, triggered and tested the fix.

Fixes: 8914f4bace3f ("sctp: add sctp_make_op_error_limited and reuse inner functions")
Cc: stable@vger.kernel.org
Signed-off-by: Masafumi Suzuki <shengshilingmu97@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20261027082405.1297-1-shengshilingmu97@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When cookie authentication is disabled, COOKIE-ECHO peer_addr is
attacker-controlled. An invalid sa_family made sctp_get_af_specific()
return NULL and crash in sctp_transport_init() on
af_specific->sockaddr_len. Validate it with af->addr_valid() in
sctp_unpack_cookie(), which also rejects a mismatched family, e.g.
an AF_INET6 peer_addr on an IPv4 socket that would later crash in
sctp_v6_get_dst() on inet6_sk(sk)->opt. Validate a copy of peer_addr,
since addr_valid() rewrites a v4-mapped v6 address in place and the
cookie still lives in the received skb, which is not guaranteed to
be unshared. Store the validated copy in the new association and
pass it to sctp_process_init() instead of the raw cookie, so a
v4-mapped v6 address is normalised to AF_INET before the association
and its primary transport are built from it.

For that, sctp_v6_addr_valid() has to return 0 for a non-v4-mapped
address when it is called with a socket that is not PF_INET6, so that
IPv6 addresses are never used on IPv4 sockets. The check is done after
the v4-mapped handling, so v4-mapped addresses passed to an IPv4
socket through the socket API keep being accepted. As addr_valid()
now also checks sk_family and ipv6_only_sock, simplify the address
handling in sctp_process_param() with it, as it additionally filters
out non-unicast addresses. As a side effect, a v4-mapped address in
an IPv6 address parameter is now normalised to AF_INET before the
transport is created, matching what the socket API paths already do.

Also add the missing !af check in sctp_process_init(), as
sctp_get_af_specific(AF_INET6) returns NULL on CONFIG_IPV6=n builds.

  BUG: KASAN: null-ptr-deref in sctp_transport_new+0xa7/0x350
  Read of size 4 at addr 00000000000000b4 by task poc/682
  Call Trace:
   <IRQ>
   sctp_transport_new+0xa7/0x350
   sctp_assoc_add_peer+0x153/0x850
   sctp_process_init+0xf9/0x1180
   sctp_sf_do_5_1D_ce+0x464/0xbc0
   sctp_do_sm+0x114/0x2990
   sctp_endpoint_bh_rcv+0x280/0x430
   sctp_inq_push+0xdd/0x100
   sctp_rcv+0x17f5/0x1ae0
   sctp4_rcv+0x2b/0x40
   ip_protocol_deliver_rcu+0x25b/0x270
   ip_local_deliver+0xd1/0xe0
   </IRQ>
  Kernel panic - not syncing: Fatal exception in interrupt

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xingyuan Mo <hdthky0@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20261019073747.178626-1-hdthky0@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Merge in late fixes in preparation for the net-next PR.

Conflicts:

net/netfilter/nf_conntrack_netlink.c
  cd37ab22a74e0 ("netfilter: nf_conntrack_netlink: fix inverted IPv6 tuple filter")
  1ae2d094b0200 ("netfilter: ctnetlink: fix inverted IPv6 address match in dump filter")

Adjacent changes:

drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.c
  8830e65ed46de ("net: use assign_bit() where applicable")
  07bd391eb957 ("octeontx2-af: Fix CQ enable state tracking after AQ writes")

net/core/sock.c
  31c5ea8a3296 ("ipv6: Remove IPV6_ADDRFORM.")
  31b564f70d88 ("net: use the full socket in sk_mc_loop()")

net/mptcp/protocol.h
  0cb6910130a3 ("mptcp: remove thmac from subflow ctx")
  7538fa33bb2f ("mptcp: fix subflow bitfield misuse")

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

skb_unshare() only copies cloned skbs. A shared skb that is not a clone
comes back unchanged, which the name doesn't suggest. The loopback
selftest hooks got caught by this and hit BUG_ON(skb_shared()).

Rename it to skb_unclone_full(). Like skb_unclone() it only acts on
clones, but it copies the whole skb, not just the head.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com> # dpaa2
Link: https://patch.msgid.link/20261015-nb-skb-unclone-full-v1-1-0dfbf01f60f2@tipi-net.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sctp_sendmsg_to_asoc() selects a transport before waiting for a new
interleaved association to become established. sctp_wait_for_connect()
drops the socket lock while sleeping.

While the lock is dropped, backlog processing can handle a COOKIE ACK and
an ASCONF DEL-IP that removes the selected transport. sctp_assoc_rm_peer()
then marks the transport dead and drops its association-owned reference.
The transport can be freed through RCU before the send path resumes.

After the wait, the stale pointer is assigned to newly created DATA or
I-DATA chunks and later dereferenced by sctp_outq_select_transport().

Hold a reference to the selected transport across
sctp_wait_for_connect(). After the socket lock is reacquired, abort the
send if the transport was marked dead. Callers without a selected
transport pass NULL and retain their existing behavior.

Cc: stable@vger.kernel.org
Fixes: 668c9beb9020 ("sctp: implement assign_number for sctp_stream_interleave")
Acked-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Seung Min Shin <guncraft2000@naver.com>
Link: https://patch.msgid.link/20261011162750.1529631-1-guncraft2000@naver.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sctp_sock_migrate() transfers DATA chunk ownership but leaves retained
control chunks pointing at the old socket. A later retransmission can
therefore access the socket after it has been freed.

Extend the migration walk to cover retained control chunks and use
sctp_control_set_owner_w() to assign their new owner. Reuse the DATA
ownership check so each chunk is processed once per pass, even when it
is reachable through multiple lists or retained pointers.

Preserve a control chunk's existing authentication key across migration
so its final release can still generate SCTP_AUTH_FREE_KEY when needed.

Fixes: d04adf1b3551 ("sctp: reset owner sk for data chunks on out queues when migrating a sock")
Cc: stable@kernel.org
Reported-by: TencentOS Corvus AI <corvus@tencent.com>
Signed-off-by: Jun Yang <junvyyang@tencent.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20261009074244.3718-3-juny24602@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sctp_sock_migrate() transfers queued DATA skbs from the old socket to the
new one. skb_orphan() invokes sctp_wfree() during that transfer and drops
the skb-owned shared-key reference.

If userspace has removed that key from the association, this can be the
final reference. The following sctp_set_owner_w() then dereferences the
freed chunk->shkey while trying to take the new owner reference.

Take a temporary shared-key reference before orphaning the skb and release
it after the new owner has taken its reference. This preserves the selected
authentication key throughout the ownership transfer.

Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.

Fixes: 1b1e0bc99474 ("sctp: add refcnt support for sh_key")
Signed-off-by: Kyle Zeng <kylebot@openai.com>
Signed-off-by: David Lee <david.lee@trailofbits.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20261009074244.3718-2-juny24602@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Cross-merge networking fixes after downstream PR (net-7.3-rc8).

No conflicts. Adjacent changes:

drivers/net/ethernet/microchip/lan865x/lan865x.c
  2a3f6d2a9ac3 ("microchip: lan865x: move setting of netops to fix crash")
  15358c2c3dca ("net: ethernet: oa_tc6: return ERR_PTR from oa_tc6_init()")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When message interleaving is enabled, the first send waits for association
establishment before building its data chunks.  The wait drops the socket
lock, and handshake processing can reduce the output stream count to the
peer-advertised inbound stream count.  sctp_stream_init() then frees the
extension of every removed stream.

The sender resumes with the stream that it checked before the wait.  If the
peer removed that stream, sctp_outq_tail() later dereferences its NULL
extension.  Fatal-oops policies then panic the host.

KASAN: null-ptr-deref in range [0x38-0x3f]
RIP: sctp_outq_tail+0x49e/0xaa0
Call Trace:
 sctp_primitive_SEND
 sctp_sendmsg_to_asoc
 sctp_sendmsg

A range check alone is insufficient.  Stream reconfiguration can grow the
output count again while the lock is released without recreating extensions
freed by the earlier shrink.  The stream can then be in range while its
extension remains NULL.  The send-buffer wait has the same issue.

Factor the range and extension checks into a helper and repeat both after
each send-path wait that drops the socket lock.  Once the lock is
reacquired, the validation remains stable through data creation and
queueing.

If validation fails after the connect wait, the auto-created association is
already established.  Return ESRCH so the existing caller path keeps it
under state-machine ownership instead of freeing it directly, which would
leave protocol, counter and socket state inconsistent.

Fixes: 668c9beb9020 ("sctp: implement assign_number for sctp_stream_interleave")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20261007035739.3472432-1-4ncienth@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Cross-merge networking fixes after downstream PR (net-7.3-rc7).

Conflicts:

include/net/strparser.h
  0984ebc631792 ("strparser: make sure __strp_recv isn't running before tearing down the parser")
  02fd0a2111374 ("net: strparser: removed the aborted bit and aborts counter")
https://lore.kernel.org/asYfmLsfy-SCxXjr@sirena.co.uk

Adjacent changes:

Documentation/networking/strparser.rst
  5f193cdabf25 ("docs: networking: strparser: remove general mode")
  0984ebc63179 ("strparser: make sure __strp_recv isn't running before tearing down the parser")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>