linux-stable.git/net/netfilter, branch v6.18.33

netfilter: nft_ct: fix missing expect put in obj eval

2026-05-23T11:07:16+00:00

commit 19f94b6fee75b3ef7fbc06f3745b9a771a8a19a4 upstream.

nft_ct_expect_obj_eval() allocates an expectation and may call
nf_ct_expect_related(), but never drops its local reference.

Add nf_ct_expect_put(exp) before return to balance allocation.

Fixes: 857b46027d6f ("netfilter: nft_ct: add ct expectations support")
Cc: stable@vger.kernel.org
Signed-off-by: Li Xiasong 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_conntrack_sip: get helper before allocating expectation

2026-05-23T11:07:15+00:00

commit eb6317739b1ea3ab28791e1f91b24781905fa815 upstream.

process_register_request() allocates an expectation and then checks
whether a conntrack helper is available. If helper lookup fails, the
function returns early and the allocated expectation is left behind.

Reorder the code to fetch and validate helper before calling
nf_ct_expect_alloc(). This keeps the logic simpler and removes the leak
path while preserving existing behavior.

Fixes: e14575fa7529 ("netfilter: nf_conntrack: use rcu accessors where needed")
Cc: stable@vger.kernel.org
Signed-off-by: Li Xiasong 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Greg Kroah-Hartman

netfilter: skip recording stale or retransmitted INIT

2026-05-23T11:07:11+00:00

[ Upstream commit 576a5d2bad4814c881a829576b1261b9b8159d2b ]

An INIT whose init_tag matches the peer's vtag does not provide new state
information. It indicates either:

- a stale INIT (after INIT-ACK has already been seen on the same side), or
- a retransmitted INIT (after INIT has already been recorded on the same
  side).

In both cases, the INIT must not update ct->proto.sctp.init[] state, since
it does not advance the handshake tracking and may otherwise corrupt
INIT/INIT-ACK validation logic.

Allow INIT processing only when the conntrack entry is newly created
(SCTP_CONNTRACK_NONE), or when the init_tag differs from the stored peer
vtag.

Note it skips the check for the ct with old_state SCTP_CONNTRACK_NONE in
nf_conntrack_sctp_packet(), as it is just created in sctp_new() where it
set ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = ih->init_tag.

Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.")
Signed-off-by: Xin Long 
Reviewed-by: Marcelo Ricardo Leitner 
Acked-by: Florian Westphal 
Link: https://patch.msgid.link/ee56c3e416452b2a40589a2a85245ac2ad5e9f4b.1777214801.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

netfilter: nf_conntrack_sip: don't use simple_strtoul

2026-05-23T11:07:07+00:00

[ Upstream commit 8cf6809cddcbe301aedfc6b51bcd4944d45795f6 ]

Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(),
and ct_sip_parse_request() with a new sip_parse_port() helper that
validates each digit against the buffer limit, eliminating the use of
simple_strtoul() which assumes NUL-terminated strings.

The previous code dereferenced pointers without bounds checks after
sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated
skb data. A port that reaches the buffer limit without a trailing
character is also rejected as malformed.

Also get rid of all simple_strtoul() usage in conntrack, prefer a
stricter version instead.  There are intentional changes:

- Bail out if number is > UINT_MAX and indicate a failure, same for
  too long sequences.
  While we do accept 05535 as port 5535, we will not accept e.g.
  'sip:10.0.0.1:005060'.  While its syntactically valid under RFC 3261,
  we should restrict this to not waste cycles when presented with
  malformed packets with 64k '0' characters.

- Force base 10 in ct_sip_parse_numerical_param(). This is used to fetch
  'expire=' and 'rports='; both are expected to use base-10.

- In nf_nat_sip.c, only accept the parsed value if its within the 1k-64k
  range.

- epaddr_len now returns 0 if the port is invalid, as it already does
  for invalid ip addresses.  This is intentional. nf_conntrack_sip
  performs lots of guesswork to find the right parts of the message
  to parse.  Being stricter could break existing setups.
  Connection tracking helpers are designed to allow traffic to
  pass, not to block it.

Based on an earlier patch from Jenny Guanni Qu .

Fixes: 05e3ced297fe ("[NETFILTER]: nf_conntrack_sip: introduce SIP-URI parsing helper")
Reported-by: Klaudia Kloc 
Reported-by: Dawid Moczadło 
Reported-by: Jenny Guanni Qu .
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: xt_policy: fix strict mode inbound policy matching

2026-05-23T11:07:07+00:00

[ Upstream commit 4b2b4d7d4e203c92db8966b163edfacb1f0e1e29 ]

match_policy_in() walks sec_path entries from the last transform to the
first one, but strict policy matching needs to consume info->pol[] in
the same forward order as the rule layout.

Derive the strict-match policy position from the number of transforms
already consumed so that multi-element inbound rules are matched
consistently.

Fixes: c4b885139203 ("[NETFILTER]: x_tables: replace IPv4/IPv6 policy match by address family independant version")
Reported-by: Yuan Tan 
Reported-by: Yifan Wu 
Reported-by: Juefei Pu 
Reported-by: Xin Liu 
Signed-off-by: Jiexun Wang 
Signed-off-by: Ren Wei 
Acked-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nf_tables: use list_del_rcu for netlink hooks

2026-05-23T11:07:07+00:00

[ Upstream commit f3224ee463f8f6f6ced7dcdf6081add4f8128527 ]

nft_netdev_unregister_hooks and __nft_unregister_flowtable_net_hooks need
to use list_del_rcu(), this list can be walked by concurrent dumpers.

Add a new helper and use it consistently.

Fixes: f9a43007d3f7 ("netfilter: nf_tables: double hook unregistration in netns path")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check

2026-05-23T11:07:02+00:00

[ Upstream commit 711987ba281fd806322a7cd244e98e2a81903114 ]

The nf_osf_ttl() function accessed skb->dev to perform a local interface
address lookup without verifying that the device pointer was valid.

Additionally, the implementation utilized an in_dev_for_each_ifa_rcu
loop to match the packet source address against local interface
addresses. It assumed that packets from the same subnet should not see a
decrement on the initial TTL. A packet might appear it is from the same
subnet but it actually isn't especially in modern environments with
containers and virtual switching.

Remove the device dereference and interface loop. Replace the logic with
a switch statement that evaluates the TTL according to the ttl_check.

Fixes: 11eeef41d5f6 ("netfilter: passive OS fingerprint xtables match")
Reported-by: Kito Xu (veritas501) 
Closes: https://lore.kernel.org/netfilter-devel/20260414074556.2512750-1-hxzene@gmail.com/
Signed-off-by: Fernando Fernandez Mancera 
Reviewed-by: Pablo Neira Ayuso 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nfnetlink_osf: fix out-of-bounds read on option matching

2026-05-23T11:07:02+00:00

[ Upstream commit f5ca450087c3baf3651055e7a6de92600f827af3 ]

In nf_osf_match(), the nf_osf_hdr_ctx structure is initialized once
and passed by reference to nf_osf_match_one() for each fingerprint
checked. During TCP option parsing, nf_osf_match_one() advances the
shared ctx->optp pointer.

If a fingerprint perfectly matches, the function returns early without
restoring ctx->optp to its initial state. If the user has configured
NF_OSF_LOGLEVEL_ALL, the loop continues to the next fingerprint.
However, because ctx->optp was not restored, the next call to
nf_osf_match_one() starts parsing from the end of the options buffer.
This causes subsequent matches to read garbage data and fail
immediately, making it impossible to log more than one match or logging
incorrect matches.

Instead of using a shared ctx->optp pointer, pass the context as a
constant pointer and use a local pointer (optp) for TCP option
traversal. This makes nf_osf_match_one() strictly stateless from the
caller's perspective, ensuring every fingerprint check starts at the
correct option offset.

Fixes: 1a6a0951fc00 ("netfilter: nfnetlink_osf: add missing fmatch check")
Suggested-by: Florian Westphal 
Signed-off-by: Fernando Fernandez Mancera 
Reviewed-by: Pablo Neira Ayuso 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

ipvs: fix MTU check for GSO packets in tunnel mode

2026-05-23T11:07:02+00:00

[ Upstream commit 67bf42cae41d847fd6e5749eb68278ca5d748b25 ]

Currently, IPVS skips MTU checks for GSO packets by excluding them with
the !skb_is_gso(skb) condition. This creates problems when IPVS tunnel
mode encapsulates GSO packets with IPIP headers.

The issue manifests in two ways:

1. MTU violation after encapsulation:
   When a GSO packet passes through IPVS tunnel mode, the original MTU
   check is bypassed. After adding the IPIP tunnel header, the packet
   size may exceed the outgoing interface MTU, leading to unexpected
   fragmentation at the IP layer.

2. Fragmentation with problematic IP IDs:
   When net.ipv4.vs.pmtu_disc=1 and a GSO packet with multiple segments
   is fragmented after encapsulation, each segment gets a sequentially
   incremented IP ID (0, 1, 2, ...). This happens because:

   a) The GSO packet bypasses MTU check and gets encapsulated
   b) At __ip_finish_output, the oversized GSO packet is split into
      separate SKBs (one per segment), with IP IDs incrementing
   c) Each SKB is then fragmented again based on the actual MTU

   This sequential IP ID allocation differs from the expected behavior
   and can cause issues with fragment reassembly and packet tracking.

Fix this by properly validating GSO packets using
skb_gso_validate_network_len(). This function correctly validates
whether the GSO segments will fit within the MTU after segmentation. If
validation fails, send an ICMP Fragmentation Needed message to enable
proper PMTU discovery.

Fixes: 4cdd34084d53 ("netfilter: nf_conntrack_ipv6: improve fragmentation handling")
Signed-off-by: Yingnan Zhang <342144303@qq.com>
Acked-by: Julian Anastasov 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nat: use kfree_rcu to release ops

2026-05-23T11:07:02+00:00

[ Upstream commit 6eda0d771f94267f73f57c94630aa47e90957915 ]

Florian Westphal says:

"Historically this is not an issue, even for normal base hooks: the data
path doesn't use the original nf_hook_ops that are used to register the
callbacks.

However, in v5.14 I added the ability to dump the active netfilter
hooks from userspace.

This code will peek back into the nf_hook_ops that are available
at the tail of the pointer-array blob used by the datapath.

The nat hooks are special, because they are called indirectly from
the central nat dispatcher hook. They are currently invisible to
the nfnl hook dump subsystem though.

But once that changes the nat ops structures have to be deferred too."

Update nf_nat_register_fn() to deal with partial exposition of the hooks
from error path which can be also an issue for nfnetlink_hook.

Fixes: e2cf17d3774c ("netfilter: add new hook nfnl subsystem")
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin