linux.git/net/netfilter, branch v7.2-rc7

Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2026-08-07T15:08:57+00:00

Pull BPF fixes from Daniel Borkmann:

 - Fix BPF verifier to preserve full pointer state for commuted
   scalar += pointer arithmetic (Yiyang Chen, Eduard Zingerman)

 - Fix a use-after-free of request sockets in the BPF TCP iterator
   batching (Jose Fernandez)

 - Fix a use-after-free of sk_redir in the BPF sockmap send verdict
   path (Chengfeng Ye)

 - Fix a netns reference imbalance in the BPF conntrack kfuncs
   (Chengfeng Ye)

 - Fix bpf_get_fsverity_digest() dynptr assumptions and silent
   digest truncation (Eric Biggers)

 - Fix bpf_tcp_{gen,check}_syncookie to check sk_state before
   sk_protocol to make sure it is a full socket (Luxiao Xu)

 - Fix rqspinlock to reset the tail when preserving the queue
   on deadlock (Kumar Kartikeya Dwivedi)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  rqspinlock: Reset tail when preserving queue on deadlock
  bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie
  fsverity: Fix silent truncation in bpf_get_fsverity_digest()
  fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions
  bpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch()
  bpf: Fix netns reference imbalance in conntrack kfuncs
  bpf, sockmap: Fix sk_redir use-after-free in send verdict
  selftests/bpf: Cover commuted pointer state propagation
  bpf: Propagate untrusted pointer state in commuted arithmetic
  bpf: Preserve pointer state for commuted arithmetic
  bpf: Simplify sanitize_err() signature

netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()

2026-08-06T00:11:18+00:00

Incoming skbs passing through netfilter flowtable offload hooks (or XFRM
offload path) might already carry a ref-counted dst_entry assigned during
earlier RX or routing steps.

Calling skb_dst_set_noref() when skb already holds a ref-counted dst
overwrites skb->_skb_refdst, leaking the previous dst_entry reference
count and triggering a DEBUG_NET_WARN_ON_ONCE assertion in
skb_dst_check_unset():

  WARNING: at skb_dst_check_unset include/linux/skbuff.h:1170
  WARNING: at skb_dst_set_noref include/linux/skbuff.h:1234
  WARNING: at nf_flow_offload_ip_hook+0xf6c/0x2b60 net/netfilter/nf_flow_table_ip.c:864

Drop any existing dst_entry reference with skb_dst_drop(skb) before
setting the non-referenced flowtable destination.

Fixes: 2a79fd3908ac ("netfilter: nf_flow_table: attach dst to skbs")
Reported-by: syzbot+76d4e3a055aec3b007ec@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6a71b141.9511d2ce.1fc5b9.033b.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet 
Reviewed-by: Pablo Neira Ayuso 
Link: https://patch.msgid.link/20260804093328.1831847-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

bpf: Fix netns reference imbalance in conntrack kfuncs

2026-08-01T18:45:24+00:00

The opts argument of the BPF conntrack kfuncs can point to a shared
map value.  __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read
opts->netns_id separately when acquiring and releasing the network
namespace reference.

The reference imbalance can occur as follows:

  CPU 0                                  CPU 1
  read opts->netns_id (-1)
  skip get_net_ns_by_id()
                                         write opts->netns_id (id)
  read opts->netns_id (id)
  put_net(net) /* no matching get */

The reverse transition leaks the reference.  Repeating the unmatched put
can destroy a live namespace and crash later users.

The kernel reported:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]
  RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700
  Call Trace:
   __sys_bpf+0x1662/0x50c0
   __x64_sys_bpf+0x73/0xb0
   do_syscall_64+0xf9/0x540
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  Kernel panic - not syncing: Fatal exception

Snapshot every input field of opts with READ_ONCE() before validating or
using it.  The netns_id snapshot keeps the namespace get/put pair
balanced, while the other snapshots keep the remaining options from
changing partway through an invocation.  The individual reads can still
observe an inconsistent combination during a concurrent update, but each
selected field value remains stable for that invocation.

Fixes: aed8ee7feb44 ("net: netfilter: Deduplicate code in bpf_{xdp,skb}_ct_lookup")
Fixes: d7e79c97c00c ("net: netfilter: Add kfuncs to allocate and insert CT")
Signed-off-by: Chengfeng Ye 
Reviewed-by: Emil Tsalapatis 
Link: https://lore.kernel.org/bpf/20260731160921.3245840-1-nicoyip.dev@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi

ipvs: return the csum validation for forward hook

2026-07-31T13:58:30+00:00

Sashiko notes that playing games with the skb dst and rt
flags instead of providing hooknum is not a good idea
when validating the checksums.

Also, skipping checksum validation for FORWARD packets
risk silent data corruption, even if the only user is
the FTP-CMD packets coming from the real server.

Sashiko also noticed that by using common checksum
helper in the previous commit we actually fixed old bug
where the TCP/UDP checksum for IPv6 on CHECKSUM_COMPLETE
was not validated correctly.

Fixes: e876b75b9020 ("ipvs: fix the checksum validations")
Link: https://sashiko.dev/#/patchset/20260722211420.153933-1-pablo%40netfilter.org
Link: https://sashiko.dev/#/patchset/20260727185024.67534-1-ja%40ssi.bg
Link: https://sashiko.dev/#/patchset/20260728202520.59179-1-ja%40ssi.bg
Signed-off-by: Julian Anastasov 
Signed-off-by: Pablo Neira Ayuso

ipvs: avoid out-of-bounds write in ip_vs_nat_icmp

2026-07-31T13:58:16+00:00

Sashiko warns that local attacker can modify the packet
while it is processed by IPVS. Some places read the
IP ihl field multiple times which can cause out-of-bounds
access. One such place is ip_vs_nat_icmp where we
can write after the validated area.

Fix it by providing ciph argument just like it is done for
IPv6 and use ciph->len as offset to the embedded transport
header.

Modify some IPv4 header checks by reading the ihl field
only once.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Link: https://sashiko.dev/#/patchset/20260722101517.36313-1-ja%40ssi.bg
Signed-off-by: Julian Anastasov 
Signed-off-by: Pablo Neira Ayuso

netfilter: ipset: switch to rcu work

2026-07-31T13:58:08+00:00

In the initial ipset rhashtable conversion RFC series syzbot reported
following splat:

BUG: sleeping function [..] at kernel/irq_work.c:289
in_atomic(): 1, [..]
 irq_work_sync.. kernel/irq_work.c:289
 rhashtable_free_and_destroy.. lib/rhashtable.c:1295
 hash_netport4_destroy.. net/netfilter/ipset/ip_set_hash_gen.h:420
 ip_set_destroy_set_rcu.. net/netfilter/ipset/ip_set_core.c:1169
 rcu_core.. kernel/rcu/tree.c:2897

This is because post-rhashtable-conversion hash implementation needs
to schedule in the destroy callback.  At this time this isn't allowed.

Replace existing call_rcu() based destruction with rcu_work api.

Also allows to undo split of set destruction and gc work cancelling in
a future patch.

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

netfilter: ipset: add and use mtype_del_cidr_all helper

2026-07-31T13:58:03+00:00

Reduces size of upcoming rhashtable conversion.

Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: ipset: add small wrappers for hash and bucket sizes

2026-07-31T13:57:53+00:00

Preparation patch.  Once the ipset hash table is replaced with rhashtable
these functions are needed. Add them in extra commit to have reviewable
chunks.

Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: ipset: switch ext_size to atomic64_t

2026-07-31T13:57:38+00:00

The hash types do not acquire set->lock, they use 'region locking' where
only part of the hash table is locked. Parallel inserts and deletes are
possible and CPUs can race on ->ext_size update.  Switch to atomic64_t.

This leaves another bug unresolved: there still can be a race on
comment extension re-init.  This will be handled in a later commit
when converting to rhashtable backend.

Fixes: f66ee0410b1c ("netfilter: ipset: Fix "INFO: rcu detected stall in hash_xxx" reports")
Signed-off-by: Jozsef Kadlecsik 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: ipset: rework cidr bookkeeping

2026-07-31T13:56:50+00:00

According to sashiko, the current bookkeeping of cidr values are unsafe
on weakly-ordered architectures. Replace the in-place updating with an
RCU based method: create the new bookeeping structure, update and replace
the old one with the new. Downside that we need to allocate memory when
deleting a cidr entry - in case of memory pressure fall back to leave holes
which possibility is taken into account at evaluation time.

Thanks to Pablo (Pablo Neira Ayuso ) and Cyntia
(Cynthia ) for helping me in debugging which resulted
the patch "netfilter: ipset: allocate the proper memory for the generic
hash structure" on which this very patch depends.

Signed-off-by: Jozsef Kadlecsik 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso