kernel/linux.git/net/netfilter, branch v5.10.257

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

2026-04-18T08:31:15+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: ipset: drop logically empty buckets in mtype_del

2026-04-18T08:31:13+00:00

commit 9862ef9ab0a116c6dca98842aab7de13a252ae02 upstream. mtype_del() counts empty slots below n->pos in k, but it only drops the bucket when both n->pos and k are zero. This misses buckets whose live entries have all been removed while n->pos still points past deleted slots. Treat a bucket as empty when all positions below n->pos are unused and release it directly instead of shrinking it further. Fixes: 8af1c6fbd923 ("netfilter: ipset: Fix forceadd evaluation path") Cc: stable@vger.kernel.org Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Yifan Wu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Reviewed-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman

netfilter: nf_tables: reject immediate NF_QUEUE verdict

2026-04-18T08:31:09+00:00

[ Upstream commit da107398cbd4bbdb6bffecb2ce86d5c9384f4cec ] nft_queue is always used from userspace nftables to deliver the NF_QUEUE verdict. Immediately emitting an NF_QUEUE verdict is never used by the userspace nft tools, so reject immediate NF_QUEUE verdicts. The arp family does not provide queue support, but such an immediate verdict is still reachable. Globally reject NF_QUEUE immediate verdicts to address this issue. Fixes: f342de4e2f33 ("netfilter: nf_tables: reject QUEUE/DROP verdict parameters") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP

2026-04-18T08:31:09+00:00

[ Upstream commit 3d5d488f11776738deab9da336038add95d342d1 ] Weiming Shi says: xt_match and xt_target structs registered with NFPROTO_UNSPEC can be loaded by any protocol family through nft_compat. When such a match/target sets .hooks to restrict which hooks it may run on, the bitmask uses NF_INET_* constants. This is only correct for families whose hook layout matches NF_INET_*: IPv4, IPv6, INET, and bridge all share the same five hooks (PRE_ROUTING ... POST_ROUTING). ARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different semantics. Because NF_ARP_OUT == 1 == NF_INET_LOCAL_IN, the .hooks validation silently passes for the wrong reasons, allowing matches to run on ARP chains where the hook assumptions (e.g. state->in being set on input hooks) do not hold. This leads to NULL pointer dereferences; xt_devgroup is one concrete example: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227] RIP: 0010:devgroup_mt+0xff/0x350 Call Trace: nft_match_eval (net/netfilter/nft_compat.c:407) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61) nf_hook_slow (net/netfilter/core.c:623) arp_xmit (net/ipv4/arp.c:666) Kernel panic - not syncing: Fatal exception in interrupt Fix it by restricting arptables to NFPROTO_ARP extensions only. Note that arptables-legacy only supports: - arpt_CLASSIFY - arpt_mangle - arpt_MARK that provide explicit NFPROTO_ARP match/target declarations. Fixes: 9291747f118d ("netfilter: xtables: add device group match") Reported-by: Xiang Mei Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent

2026-04-18T08:31:09+00:00

[ Upstream commit 35177c6877134a21315f37d57a5577846225623e ] ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation. Fixes: 076a0ca02644 ("netfilter: ctnetlink: add NAT support for expectations") Reported-by: kernel test robot Signed-off-by: Qi Tang Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nf_conntrack_helper: pass helper to expect cleanup

2026-04-18T08:31:09+00:00

[ Upstream commit a242a9ae58aa46ff7dae51ce64150a93957abe65 ] nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0) Fixes: ac7b84839003 ("netfilter: expect: add and use nf_ct_expect_iterate helpers") Signed-off-by: Qi Tang Reviewed-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ipset: use nla_strcmp for IPSET_ATTR_NAME attr

2026-04-18T08:31:09+00:00

[ Upstream commit b7e8590987aa94c9dc51518fad0e58cb887b1db5 ] IPSET_ATTR_NAME and IPSET_ATTR_NAMEREF are of NLA_STRING type, they cannot be treated like a c-string. They either have to be switched to NLA_NUL_STRING, or the compare operations need to use the nla functions. Fixes: f830837f0eed ("netfilter: ipset: list:set set type support") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: x_tables: ensure names are nul-terminated

2026-04-18T08:31:09+00:00

[ Upstream commit a958a4f90ddd7de0800b33ca9d7b886b7d40f74e ] Reject names that lack a \0 character before feeding them to functions that expect c-strings. Fixes tag is the most recent commit that needs this change. Fixes: c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nfnetlink_log: account for netlink header size

2026-04-18T08:31:09+00:00

[ Upstream commit 6d52a4a0520a6696bdde51caa11f2d6821cd0c01 ] This is a followup to an old bug fix: NLMSG_DONE needs to account for the netlink header size, not just the attribute size. This can result in a WARN splat + drop of the netlink message, but other than this there are no ill effects. Fixes: 9dfa1dfe4d5e ("netfilter: nf_log: account for size of NLMSG_DONE attribute") Reported-by: Yiming Qian Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ctnetlink: use netlink policy range checks

2026-04-18T08:31:05+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