kernel/linux.git/net/bridge/netfilter, branch v6.12.107

netfilter: bridge: release template ct on non-IP path

2026-08-19T16:14:26+00:00

commit d45cc8020d7c0a9f01dee42ff5c40bc14c9af72f upstream. A bridge nftables ct zone set rule can attach a conntrack template to an skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6 EtherTypes, nf_ct_bridge_pre() currently overwrites skb->_nfct with IP_CT_UNTRACKED without releasing the existing template reference. That makes the per-cpu template, and any temporary templates allocated for concurrent use, unreachable and leaks memory until the host runs out of slab. Reset the skb conntrack state before marking the frame untracked so the existing template reference is dropped on the non-IP path. Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman

netfilter: ebt_nflog: pin the NFLOG backend

2026-08-19T16:14:19+00:00

commit 30825970339c107bacaf7f61af90fcdb1f597ca1 upstream. nf_log_unregister() runs after the per-net teardown so its final RCU grace period also drains readers that obtained the logger from a per-net binding. However, ebt_nflog passes an explicit ULOG log type to nf_log_packet() without holding a reference on the selected logger module, unlike the xt_NFLOG and nft_log frontends. An ebtables nflog rule can therefore remain callable while nfnetlink_log is unloaded. The resulting interleaving is: CPU 0 CPU 1 nfnetlink_log_fini() unregister_pernet_subsys() kfree(nfnl_log_pernet(net)) ebt_nflog_tg() nf_log_packet() nfulnl_log_packet() instance_lookup_get_rcu() The global ULOG logger is still registered at this point, so CPU 1 dereferences the per-net state after CPU 0 has freed it. KASAN reported: BUG: KASAN: slab-use-after-free in instance_lookup_get_rcu Read of size 8 at addr ff110001052e6210 by task poc/92 Call Trace: instance_lookup_get_rcu+0x1ce/0x1f0 [nfnetlink_log] nfulnl_log_packet+0x248/0x2fb0 [nfnetlink_log] nf_log_packet+0x204/0x300 ebt_nflog_tg+0x351/0x550 ebt_do_table+0xedf/0x22b0 Allocated by task 90: __kmalloc_noprof+0x186/0x470 ops_init+0x6d/0x420 register_pernet_operations+0x2f6/0x670 register_pernet_subsys+0x23/0x40 Freed by task 93: kfree+0x131/0x3c0 ops_undo_list+0x3e3/0x700 unregister_pernet_operations+0x232/0x490 unregister_pernet_subsys+0x1c/0x30 nfnetlink_log_fini+0x34/0x450 [nfnetlink_log] Acquire the ULOG logger module reference when an ebt_nflog rule is validated and release it when the rule is destroyed. Request the NFLOG backend for legacy callers when needed, matching xt_NFLOG. This prevents module teardown until all ebt_nflog rules have stopped using the logger. Fixes: c83fa19603bd ("netfilter: nf_log: don't call synchronize_rcu in nf_log_unset") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman

netfilter: nf_tables: remove register tracking infrastructure

2026-08-03T09:17:33+00:00

[ Upstream commit 6b94d081f81dd524626f7aab2b98a9de335edb72 ] This facility was disabled in commit 9e539c5b6d9c ("netfilter: nf_tables: disable expression reduction infra"), because not all nft_exprs guarantee they will update the destination register: some may set NFT_BREAK instead to cancel evaluation of the rule. This has been dead code ever since. There are no plans to salvage this at this time, so remove this. Signed-off-by: Florian Westphal Link: https://patch.msgid.link/20260224205048.4718-10-fw@strlen.de Signed-off-by: Jakub Kicinski Stable-dep-of: d07955dd34ec ("netfilter: nft_fib: reject fib expression on the netdev egress hook") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfilter: ebtables: zero chainstack array

2026-07-24T14:11:49+00:00

[ Upstream commit cbfe53599eebffd188938ab6774cc41794f6f9d5 ] sashiko reports: looking at ebtables table translation, could a sparse cpu_possible_mask lead to an uninitialized pointer free? If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible, but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at CPU 2, the cleanup loop will blindly decrement and call vfree() on newinfo->chainstack[1]. Not a real-world bug, such allocation isn't expected to fail in the first place. Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfilter: ebtables: Use vmalloc_array() to improve code

2026-07-24T14:11:49+00:00

[ Upstream commit 46015e6b3ea75297b28d4806564f3f692cf11861 ] Remove array_size() calls and replace vmalloc() with vmalloc_array() to simplify the code. vmalloc_array() is also optimized better, uses fewer instructions, and handles overflow more concisely[1]. [1]: https://lore.kernel.org/lkml/abc66ec5-85a4-47e1-9759-2f60ab111971@vivo.com/ Signed-off-by: Qianfeng Rong Signed-off-by: Florian Westphal Stable-dep-of: cbfe53599eeb ("netfilter: ebtables: zero chainstack array") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfilter: nft_meta_bridge: fix NFT_META_BRI_IIFPVID stack leak

2026-07-24T14:11:12+00:00

[ Upstream commit 27dd2997746d54ebc079bb13161cc1bdd401d4a6 ] This needs to test for nonzero retval. Fixes: c54c7c685494 ("netfilter: nft_meta_bridge: add NFT_META_BRI_IIFPVID support") Closes: https://sashiko.dev/#/patchset/20260618061631.21919-1-fw%40strlen.de Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: terminate table name before find_table_lock()

2026-07-18T14:52:03+00:00

commit a622d2e9608c9dff47fc2e5759ac7aa3a836b45d upstream. update_counters() and compat_update_counters() forward a user-supplied 32-byte table name to find_table_lock() without NUL-terminating it. On a lookup miss, find_inlist_lock() calls try_then_request_module(..., "%s%s", "ebtable_", name), and vsnprintf() reads past the name field and the stack object until it hits a zero byte. BUG: KASAN: stack-out-of-bounds in string (lib/vsprintf.c:648 lib/vsprintf.c:730) Read of size 1 at addr ffff8880119dfb20 by task exploit/147 Call Trace: ... string (lib/vsprintf.c:648 lib/vsprintf.c:730) vsnprintf (lib/vsprintf.c:2945) __request_module (kernel/module/kmod.c:150) do_update_counters.isra.0 (net/bridge/netfilter/ebtables.c:371 net/bridge/netfilter/ebtables.c:380) update_counters (net/bridge/netfilter/ebtables.c:1440) do_ebt_set_ctl (net/bridge/netfilter/ebtables.c:2573) nf_setsockopt (net/netfilter/nf_sockopt.c:101) ip_setsockopt (net/ipv4/ip_sockglue.c:1424) raw_setsockopt (net/ipv4/raw.c:847) __sys_setsockopt (net/socket.c:2393) ... compat_do_replace() shares the same unterminated name via compat_copy_ebt_replace_from_user(); terminate it there too so all find_table_lock() callers behave alike. The other callers already terminate the name after the copy. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support") Cc: stable@vger.kernel.org Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

netfilter: ebtables: module names must be null-terminated

2026-07-18T14:52:03+00:00

commit 084d23f818321390509e9738a0b08bbf46df6425 upstream. We need to explicitly check the length, else we may pass non-null terminated string to request_module(). Cc: stable@vger.kernel.org Fixes: bcf493428840 ("netfilter: ebtables: Fix extension lookup with identical name") Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

netfilter: revalidate bridge ports

2026-06-19T11:42:25+00:00

[ Upstream commit ccb9fd4b87538ccf19ccff78ee26700526d94867 ] ebt_redirect_tg() dereferences br_port_get_rcu() return without a NULL check, causing a kernel panic when the bridge port has been removed between the original hook invocation and an NFQUEUE reinject. A mere NULL check isn't sufficient, however. As sashiko review points out userspace can not only remove the port from the bridge, it could also place the device in a different virtual device, e.g. macvlan. If this happens, we must drop the packet, there is no way for us to reinject it into the bridge path. Switch to _upper API, we don't need the bridge port structure. Also, this fix keeps another bug intact: Both nfnetlink_log and nfnetlink_queue use CONFIG_BRIDGE_NETFILTER too aggressive, which prevents certain logging features when queueing in bridge family: NETFILTER_FAMILY_BRIDGE can be enabled while the old CONFIG_BRIDGE_NETFILTER cruft is off. Fixes tag is a common ancestor, this was always broken. Fixes: f350a0a87374 ("bridge: use rx_handler_data pointer to store net_bridge_port pointer") Reported-by: Ji'an Zhou Assisted-by: Claude:claude-sonnet-4-6 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: bridge: make ebt_snat ARP rewrite writable

2026-06-19T11:42:19+00:00

[ Upstream commit 67ba971ae02514d85818fe0c32549ab4bfa3bf49 ] The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is intentional: at the bridge ebtables hooks the Ethernet header is addressed through skb_mac_header()/eth_hdr(), while skb->data points at the Ethernet payload. Asking skb_ensure_writable() for ETH_HLEN bytes would check the payload, not the Ethernet header, and would reintroduce the small packet regression fixed by commit 63137bc5882a. However, the optional ARP sender hardware address rewrite is different. It writes through skb_store_bits() at an offset relative to skb->data: skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN) skb_header_pointer() only safely reads the ARP header; it does not make the later sender hardware address range writable. If that range is still held in a nonlinear skb fragment backed by a splice-imported file page, skb_store_bits() maps the frag page and copies the new MAC address directly into it. Ensure the ARP SHA range is writable before reading the ARP header and before calling skb_store_bits(). Fixes: 63137bc5882a ("netfilter: ebtables: Fixes dropping of small packets in bridge nat") Reported-by: Yiming Qian Signed-off-by: Yiming Qian Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin