linux-stable.git/include/net/netfilter, branch v6.18.26

netfilter: nfnetlink_queue: make hash table per queue

2026-04-22T11:22:23+00:00

[ Upstream commit 936206e3f6ff411581e615e930263d6f8b78df9d ]

Sharing a global hash table among all queues is tempting, but
it can cause crash:

BUG: KASAN: slab-use-after-free in nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue]
[..]
 nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue]
 nfnetlink_rcv_msg+0x46a/0x930
 kmem_cache_alloc_node_noprof+0x11e/0x450

struct nf_queue_entry is freed via kfree, but parallel cpu can still
encounter such an nf_queue_entry when walking the list.

Alternative fix is to free the nf_queue_entry via kfree_rcu() instead,
but as we have to alloc/free for each skb this will cause more mem
pressure.

Cc: Scott Mitchell 
Fixes: e19079adcd26 ("netfilter: nfnetlink_queue: optimize verdict lookup with hash table")
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: ctnetlink: ensure safe access to master conntrack

2026-04-22T11:22:13+00:00

[ Upstream commit bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5 ]

Holding reference on the expectation is not sufficient, the master
conntrack object can just go away, making exp->master invalid.

To access exp->master safely:

- Grab the nf_conntrack_expect_lock, this gets serialized with
  clean_from_lists() which also holds this lock when the master
  conntrack goes away.

- Hold reference on master conntrack via nf_conntrack_find_get().
  Not so easy since the master tuple to look up for the master conntrack
  is not available in the existing problematic paths.

This patch goes for extending the nf_conntrack_expect_lock section
to address this issue for simplicity, in the cases that are described
below this is just slightly extending the lock section.

The add expectation command already holds a reference to the master
conntrack from ctnetlink_create_expect().

However, the delete expectation command needs to grab the spinlock
before looking up for the expectation. Expand the existing spinlock
section to address this to cover the expectation lookup. Note that,
the nf_ct_expect_iterate_net() calls already grabs the spinlock while
iterating over the expectation table, which is correct.

The get expectation command needs to grab the spinlock to ensure master
conntrack does not go away. This also expands the existing spinlock
section to cover the expectation lookup too. I needed to move the
netlink skb allocation out of the spinlock to keep it GFP_KERNEL.

For the expectation events, the IPEXP_DESTROY event is already delivered
under the spinlock, just move the delivery of IPEXP_NEW under the
spinlock too because the master conntrack event cache is reached through
exp->master.

While at it, add lockdep notations to help identify what codepaths need
to grab the spinlock.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Sasha Levin

netfilter: nft_ct: fix use-after-free in timeout object destroy

2026-04-18T08:44:58+00:00

commit f8dca15a1b190787bbd03285304b569631160eda upstream.

nft_ct_timeout_obj_destroy() frees the timeout object with kfree()
immediately after nf_ct_untimeout(), without waiting for an RCU grace
period. Concurrent packet processing on other CPUs may still hold
RCU-protected references to the timeout object obtained via
rcu_dereference() in nf_ct_timeout_data().

Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer
freeing until after an RCU grace period, matching the approach already
used in nfnetlink_cttimeout.c.

KASAN report:
 BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0
 Read of size 4 at addr ffff8881035fe19c by task exploit/80

 Call Trace:
  nf_conntrack_tcp_packet+0x1381/0x29d0
  nf_conntrack_in+0x612/0x8b0
  nf_hook_slow+0x70/0x100
  __ip_local_out+0x1b2/0x210
  tcp_sendmsg_locked+0x722/0x1580
  __sys_sendto+0x2d8/0x320

 Allocated by task 75:
  nft_ct_timeout_obj_init+0xf6/0x290
  nft_obj_init+0x107/0x1b0
  nf_tables_newobj+0x680/0x9c0
  nfnetlink_rcv_batch+0xc29/0xe00

 Freed by task 26:
  nft_obj_destroy+0x3f/0xa0
  nf_tables_trans_destroy_work+0x51c/0x5c0
  process_one_work+0x2c4/0x5a0

Fixes: 7e0b2b57f01d ("netfilter: nft_ct: add ct timeout support")
Cc: stable@vger.kernel.org
Signed-off-by: Tuan Do 
Signed-off-by: Florian Westphal 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_conntrack_expect: store netns and zone in expectation

2026-04-11T12:26:26+00:00

[ Upstream commit 02a3231b6d82efe750da6554ebf280e4a6f78756 ]

__nf_ct_expect_find() and nf_ct_expect_find_get() are called under
rcu_read_lock() but they dereference the master conntrack via
exp->master.

Since the expectation does not hold a reference on the master conntrack,
this could be dying conntrack or different recycled conntrack than the
real master due to SLAB_TYPESAFE_RCU.

Store the netns, the master_tuple and the zone in struct
nf_conntrack_expect as a safety measure.

This patch is required by the follow up fix not to dump expectations
that do not belong to this netns.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Stable-dep-of: 917b61fa2042 ("netfilter: ctnetlink: ignore explicit helper on new expectations")
Signed-off-by: Sasha Levin

netfilter: nf_conntrack_expect: honor expectation helper field

2026-04-11T12:26:25+00:00

[ Upstream commit 9c42bc9db90a154bc61ae337a070465f3393485a ]

The expectation helper field is mostly unused. As a result, the
netfilter codebase relies on accessing the helper through exp->master.

Always set on the expectation helper field so it can be used to reach
the helper.

nf_ct_expect_init() is called from packet path where the skb owns
the ct object, therefore accessing exp->master for the newly created
expectation is safe. This saves a lot of updates in all callsites
to pass the ct object as parameter to nf_ct_expect_init().

This is a preparation patches for follow up fixes.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Stable-dep-of: 917b61fa2042 ("netfilter: ctnetlink: ignore explicit helper on new expectations")
Signed-off-by: Sasha Levin

nf_tables: nft_dynset: fix possible stateful expression memleak in error path

2026-03-25T10:10:40+00:00

[ Upstream commit 0548a13b5a145b16e4da0628b5936baf35f51b43 ]

If cloning the second stateful expression in the element via GFP_ATOMIC
fails, then the first stateful expression remains in place without being
released.

   unreferenced object (percpu) 0x607b97e9cab8 (size 16):
     comm "softirq", pid 0, jiffies 4294931867
     hex dump (first 16 bytes on cpu 3):
       00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     backtrace (crc 0):
       pcpu_alloc_noprof+0x453/0xd80
       nft_counter_clone+0x9c/0x190 [nf_tables]
       nft_expr_clone+0x8f/0x1b0 [nf_tables]
       nft_dynset_new+0x2cb/0x5f0 [nf_tables]
       nft_rhash_update+0x236/0x11c0 [nf_tables]
       nft_dynset_eval+0x11f/0x670 [nf_tables]
       nft_do_chain+0x253/0x1700 [nf_tables]
       nft_do_chain_ipv4+0x18d/0x270 [nf_tables]
       nf_hook_slow+0xaa/0x1e0
       ip_local_deliver+0x209/0x330

Fixes: 563125a73ac3 ("netfilter: nftables: generalize set extension to support for several expressions")
Reported-by: Gurpreet Shergill 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: nft_set_pipapo: split gc into unlink and reclaim phase

2026-03-12T11:10:00+00:00

[ Upstream commit 9df95785d3d8302f7c066050117b04cd3c2048c2 ]

Yiming Qian reports Use-after-free in the pipapo set type:
  Under a large number of expired elements, commit-time GC can run for a very
  long time in a non-preemptible context, triggering soft lockup warnings and
  RCU stall reports (local denial of service).

We must split GC in an unlink and a reclaim phase.

We cannot queue elements for freeing until pointers have been swapped.
Expired elements are still exposed to both the packet path and userspace
dumpers via the live copy of the data structure.

call_rcu() does not protect us: dump operations or element lookups starting
after call_rcu has fired can still observe the free'd element, unless the
commit phase has made enough progress to swap the clone and live pointers
before any new reader has picked up the old version.

This a similar approach as done recently for the rbtree backend in commit
35f83a75529a ("netfilter: nft_set_rbtree: don't gc elements on insert").

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: Yiming Qian 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

netfilter: nf_tables: clone set on flush only

2026-03-12T11:10:00+00:00

[ Upstream commit fb7fb4016300ac622c964069e286dc83166a5d52 ]

Syzbot with fault injection triggered a failing memory allocation with
GFP_KERNEL which results in a WARN splat:

iter.err
WARNING: net/netfilter/nf_tables_api.c:845 at nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845, CPU#0: syz.0.17/5992
Modules linked in:
CPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845
Code: 8b 05 86 5a 4e 09 48 3b 84 24 a0 00 00 00 75 62 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 63 6d fa f7 90 <0f> 0b 90 43
+80 7c 35 00 00 0f 85 23 fe ff ff e9 26 fe ff ff 89 d9
RSP: 0018:ffffc900045af780 EFLAGS: 00010293
RAX: ffffffff89ca45bd RBX: 00000000fffffff4 RCX: ffff888028111e40
RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000
RBP: ffffc900045af870 R08: 0000000000400dc0 R09: 00000000ffffffff
R10: dffffc0000000000 R11: fffffbfff1d141db R12: ffffc900045af7e0
R13: 1ffff920008b5f24 R14: dffffc0000000000 R15: ffffc900045af920
FS:  000055557a6a5500(0000) GS:ffff888125496000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb5ea271fc0 CR3: 000000003269e000 CR4: 00000000003526f0
Call Trace:
 
 __nft_release_table+0xceb/0x11f0 net/netfilter/nf_tables_api.c:12115
 nft_rcv_nl_event+0xc25/0xdb0 net/netfilter/nf_tables_api.c:12187
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380
 netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761
 __sock_release net/socket.c:662 [inline]
 sock_close+0xc3/0x240 net/socket.c:1455

Restrict set clone to the flush set command in the preparation phase.
Add NFT_ITER_UPDATE_CLONE and use it for this purpose, update the rbtree
and pipapo backends to only clone the set when this iteration type is
used.

As for the existing NFT_ITER_UPDATE type, update the pipapo backend to
use the existing set clone if available, otherwise use the existing set
representation. After this update, there is no need to clone a set that
is being deleted, this includes bound anonymous set.

An alternative approach to NFT_ITER_UPDATE_CLONE is to add a .clone
interface and call it from the flush set path.

Reported-by: syzbot+4924a0edc148e8b4b342@syzkaller.appspotmail.com
Fixes: 3f1d886cc7c3 ("netfilter: nft_set_pipapo: move cloning of match info to insert/removal path")
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Signed-off-by: Sasha Levin

Revert "netfilter: nft_set_rbtree: validate open interval overlap"

2026-03-12T11:09:44+00:00

This reverts commit 12b1681793e9b7552495290785a3570c539f409d which is
commit 648946966a08e4cb1a71619e3d1b12bd7642de7b upstream.

It is causing netfilter issues, so revert it for now.

Link: https://lore.kernel.org/r/aaeEd8UqYQ33Af7_@chamomile
Cc: Pablo Neira Ayuso 
Cc: Florian Westphal 
Signed-off-by: Greg Kroah-Hartman

netfilter: nf_tables: add .abort_skip_removal flag for set types

2026-02-27T21:05:10+00:00

commit f175b46d9134f708358b5404730c6dfa200fbf3c upstream.

The pipapo set backend is the only user of the .abort interface so far.
To speed up pipapo abort path, removals are skipped.

The follow up patch updates the rbtree to use to build an array of
ordered elements, then use binary search. This needs a new .abort
interface but, unlike pipapo, it also need to undo/remove elements.

Add a flag and use it from the pipapo set backend.

Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Cc: "Kris Karas (Bug Reporting)" 
Cc: Genes Lists 
Cc: Philip Müller 
Signed-off-by: Greg Kroah-Hartman