linux.git/net/netfilter, branch v6.12.80

netfilter: ctnetlink: use netlink policy range checks

2026-04-02T11:09:37+00:00

[ Upstream commit 8f15b5071b4548b0aafc03b366eb45c9c6566704 ]

Replace manual range and mask validations with netlink policy
annotations in ctnetlink code paths, so that the netlink core rejects
invalid values early and can generate extack errors.

- CTA_PROTOINFO_TCP_STATE: reject values > TCP_CONNTRACK_SYN_SENT2 at
  policy level, removing the manual >= TCP_CONNTRACK_MAX check.
- CTA_PROTOINFO_TCP_WSCALE_ORIGINAL/REPLY: reject values > TCP_MAX_WSCALE
  (14). The normal TCP option parsing path already clamps to this value,
  but the ctnetlink path accepted 0-255, causing undefined behavior when
  used as a u32 shift count.
- CTA_FILTER_ORIG_FLAGS/REPLY_FLAGS: use NLA_POLICY_MASK with
  CTA_FILTER_F_ALL, removing the manual mask checks.
- CTA_EXPECT_FLAGS: use NLA_POLICY_MASK with NF_CT_EXPECT_MASK, adding
  a new mask define grouping all valid expect flags.

Extracted from a broader nf-next patch by Florian Westphal, scoped to
ctnetlink for the fixes tree.

Fixes: c8e2078cfe41 ("[NETFILTER]: ctnetlink: add support for internal tcp connection tracking flags handling")
Signed-off-by: David Carlier 
Co-developed-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp

2026-04-02T11:09:37+00:00

[ Upstream commit 6a2b724460cb67caed500c508c2ae5cf012e4db4 ]

process_sdp() declares union nf_inet_addr rtp_addr on the stack and
passes it to the nf_nat_sip sdp_session hook after walking the SDP
media descriptions. However rtp_addr is only initialized inside the
media loop when a recognized media type with a non-zero port is found.

If the SDP body contains no m= lines, only inactive media sections
(m=audio 0 ...) or only unrecognized media types, rtp_addr is never
assigned. Despite that, the function still calls hooks->sdp_session()
with &rtp_addr, causing nf_nat_sdp_session() to format the stale stack
value as an IP address and rewrite the SDP session owner and connection
lines with it.

With CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this
results in the session-level o= and c= addresses being rewritten to
0.0.0.0 for inactive SDP sessions. Without stack auto-init the
rewritten address is whatever happened to be on the stack.

Fix this by pre-initializing rtp_addr from the session-level connection
address (caddr) when available, and tracking via a have_rtp_addr flag
whether any valid address was established. Skip the sdp_session hook
entirely when no valid address exists.

Fixes: 4ab9e64e5e3c ("[NETFILTER]: nf_nat_sip: split up SDP mangling")
Reported-by: Xiang Mei 
Signed-off-by: Weiming Shi 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nf_conntrack_expect: skip expectations in other netns via proc

2026-04-02T11:09:37+00:00

[ Upstream commit 3db5647984de03d9cae0dcddb509b058351f0ee4 ]

Skip expectations that do not reside in this netns.

Similar to e77e6ff502ea ("netfilter: conntrack: do not dump other netns's
conntrack entries via proc").

Fixes: 9b03f38d0487 ("netfilter: netns nf_conntrack: per-netns expectations")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD

2026-04-02T11:09:36+00:00

[ Upstream commit 52025ebaa29f4eb4ed8bf92ce83a68f24ab7fdf7 ]

__build_packet_message() manually constructs the NFULA_PAYLOAD netlink
attribute using skb_put() and skb_copy_bits(), bypassing the standard
nla_reserve()/nla_put() helpers. While nla_total_size(data_len) bytes
are allocated (including NLA alignment padding), only data_len bytes
of actual packet data are copied. The trailing nla_padlen(data_len)
bytes (1-3 when data_len is not 4-byte aligned) are never initialized,
leaking stale heap contents to userspace via the NFLOG netlink socket.

Replace the manual attribute construction with nla_reserve(), which
handles the tailroom check, header setup, and padding zeroing via
__nla_reserve(). The subsequent skb_copy_bits() fills in the payload
data on top of the properly initialized attribute.

Fixes: df6fb868d611 ("[NETFILTER]: nfnetlink: convert to generic netlink attribute functions")
Reported-by: Xiang Mei 
Signed-off-by: Weiming Shi 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

nfnetlink_osf: validate individual option lengths in fingerprints

2026-03-25T10:08:55+00:00

[ Upstream commit dbdfaae9609629a9569362e3b8f33d0a20fd783c ]

nfnl_osf_add_callback() validates opt_num bounds and string
NUL-termination but does not check individual option length fields.
A zero-length option causes nf_osf_match_one() to enter the option
matching loop even when foptsize sums to zero, which matches packets
with no TCP options where ctx->optp is NULL:

 Oops: general protection fault
 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
 RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)
 Call Trace:
  nf_osf_match (net/netfilter/nfnetlink_osf.c:227)
  xt_osf_match_packet (net/netfilter/xt_osf.c:32)
  ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)
  nf_hook_slow (net/netfilter/core.c:623)
  ip_local_deliver (net/ipv4/ip_input.c:262)
  ip_rcv (net/ipv4/ip_input.c:573)

Additionally, an MSS option (kind=2) with length < 4 causes
out-of-bounds reads when nf_osf_match_one() unconditionally accesses
optp[2] and optp[3] for MSS value extraction.  While RFC 9293
section 3.2 specifies that the MSS option is always exactly 4
bytes (Kind=2, Length=4), the check uses "< 4" rather than
"!= 4" because lengths greater than 4 do not cause memory
safety issues -- the buffer is guaranteed to be at least
foptsize bytes by the ctx->optsize == foptsize check.

Reject fingerprints where any option has zero length, or where an MSS
option has length less than 4, at add time rather than trusting these
values in the packet matching hot path.

Fixes: 11eeef41d5f6 ("netfilter: passive OS fingerprint xtables match")
Reported-by: Xiang Mei 
Signed-off-by: Weiming Shi 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: nf_tables: release flowtable after rcu grace period on error

2026-03-25T10:08:55+00:00

[ Upstream commit d73f4b53aaaea4c95f245e491aa5eeb8a21874ce ]

Call synchronize_rcu() after unregistering the hooks from error path,
since a hook that already refers to this flowtable can be already
registered, exposing this flowtable to packet path and nfnetlink_hook
control plane.

This error path is rare, it should only happen by reaching the maximum
number hooks or by failing to set up to hardware offload, just call
synchronize_rcu().

There is a check for already used device hooks by different flowtable
that could result in EEXIST at this late stage. The hook parser can be
updated to perform this check earlier to this error path really becomes
rarely exercised.

Uncovered by KASAN reported as use-after-free from nfnetlink_hook path
when dumping hooks.

Fixes: 3b49e2e94e6e ("netfilter: nf_tables: add flow table netlink frontend")
Reported-by: Yiming Qian 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: bpf: defer hook memory release until rcu readers are done

2026-03-25T10:08:55+00:00

[ Upstream commit 24f90fa3994b992d1a09003a3db2599330a5232a ]

Yiming Qian reports UaF when concurrent process is dumping hooks via
nfnetlink_hooks:

BUG: KASAN: slab-use-after-free in nfnl_hook_dump_one.isra.0+0xe71/0x10f0
Read of size 8 at addr ffff888003edbf88 by task poc/79
Call Trace:
 
 nfnl_hook_dump_one.isra.0+0xe71/0x10f0
 netlink_dump+0x554/0x12b0
 nfnl_hook_get+0x176/0x230
 [..]

Defer release until after concurrent readers have completed.

Reported-by: Yiming Qian 
Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()

2026-03-25T10:08:53+00:00

[ Upstream commit f173d0f4c0f689173f8cdac79991043a4a89bf66 ]

In DecodeQ931(), the UserUserIE code path reads a 16-bit length from
the packet, then decrements it by 1 to skip the protocol discriminator
byte before passing it to DecodeH323_UserInformation(). If the encoded
length is 0, the decrement wraps to -1, which is then passed as a
large value to the decoder, leading to an out-of-bounds read.

Add a check to ensure len is positive after the decrement.

Fixes: 5e35941d9901 ("[NETFILTER]: Add H.323 conntrack/NAT helper")
Reported-by: Klaudia Kloc 
Reported-by: Dawid Moczadło 
Tested-by: Jenny Guanni Qu 
Signed-off-by: Jenny Guanni Qu 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: xt_time: use unsigned int for monthday bit shift

2026-03-25T10:08:53+00:00

[ Upstream commit 00050ec08cecfda447e1209b388086d76addda3a ]

The monthday field can be up to 31, and shifting a signed integer 1
by 31 positions (1 << 31) is undefined behavior in C, as the result
overflows a 32-bit signed int. Use 1U to ensure well-defined behavior
for all valid monthday values.

Change the weekday shift to 1U as well for consistency.

Fixes: ee4411a1b1e0 ("[NETFILTER]: x_tables: add xt_time match")
Reported-by: Klaudia Kloc 
Reported-by: Dawid Moczadło 
Tested-by: Jenny Guanni Qu 
Signed-off-by: Jenny Guanni Qu 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: xt_CT: drop pending enqueued packets on template removal

2026-03-25T10:08:53+00:00

[ Upstream commit f62a218a946b19bb59abdd5361da85fa4606b96b ]

Templates refer to objects that can go away while packets are sitting in
nfqueue refer to:

- helper, this can be an issue on module removal.
- timeout policy, nfnetlink_cttimeout might remove it.

The use of templates with zone and event cache filter are safe, since
this just copies values.

Flush these enqueued packets in case the template rule gets removed.

Fixes: 24de58f46516 ("netfilter: xt_CT: allow to attach timeout policy + glue code")
Reported-by: Yiming Qian 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin