wireguard-linux, branch stable

wireguard: queueing: preserve tstamp_type when encapsulating packet

2026-08-31T03:22:06Z

Sending traffic through a wireguard tunnel on a host using the fq qdisc fills the log with: fq: likely mono tstamp with tstamp_type 0 An skb carries a timestamp in skb->tstamp and, separately, a skb->tstamp_type field recording which clock that timestamp came from. The two have to agree. When wireguard encapsulates a packet it calls wg_reset_packet(), which clears the fields that must not leak from the inner packet into the tunnel packet. It does so in two steps: skb_scrub_packet(skb, true); memset(&skb->headers, 0, sizeof(skb->headers)); skb_scrub_packet() deliberately keeps skb->tstamp when it holds a monotonic timestamp: that value is the time the packet is scheduled to be sent, and the qdisc still needs it. The memset then zeroes skb->tstamp_type, because that field sits inside the headers group while skb->tstamp does not. The packet therefore leaves wireguard carrying a monotonic timestamp labelled as a realtime one. Nothing noticed until commit c4f796c4f16b ("net_sched: sch_fq: convert skb->tstamp if not monotonic"): fq used to assume every timestamp was monotonic. It now consults tstamp_type, spots the mismatch, warns, and falls back to treating the value as monotonic. Pacing still ends up correct, so the log spam is the actual problem. Save tstamp_type before the memset and restore it when encapsulating, next to the hash fields that are already carried over this way. When decapsulating it stays zeroed, which is right: an incoming packet's timestamp is a realtime receive timestamp. Fixes: de799101519a ("net: Add skb_clear_tstamp() to keep the mono delivery_time") Signed-off-by: Ramses de Norre Reviewed-by: Toke Høiland-Jørgensen Reviewed-by: Eric Dumazet Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld

wireguard: noise: remove unused variable

2026-08-31T03:18:38Z

This is a harmless artifact from early pre-release wireguard development. These days, static_private is read from a shared data structure under a read lock directly, and it doesn't need to be copied to the stack. So remove the unused variable. Signed-off-by: Jason A. Donenfeld

ipvlan: unregister upper devices outside pnodes_lock

2026-08-30T21:30:59Z

syzbot reported the following circular locking dependency: xs->mutex -> netdev lock -> pnodes_lock -> net->xdp.lock -> xs->mutex The pnodes_lock -> net->xdp.lock edge is recorded when ipvlan_device_event(NETDEV_UNREGISTER) calls unregister_netdevice_many() while holding pnodes_lock. A nested NETDEV_UNREGISTER notification for an IPvlan device enters xsk_notifier(), which acquires net->xdp.lock. Keep pnodes_lock only while marking the upper devices as dying, removing them from port->ipvlans, and queueing them for unregistration. Once the devices have been detached from the protected list, release pnodes_lock before unregister_netdevice_many() invokes notifier callbacks. The port remains alive across unregistration because ipvlan_device_event() holds the reference acquired by ipvlan_port_get(). The dying flag prevents a concurrent ->dellink() callback from deleting a queued device again. Fixes: 35add1093e2f ("ipvlan: Protect ipvl_port.ipvlans with mutex.") Reported-by: syzbot+aa48b5fe7bfda62d1682@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=aa48b5fe7bfda62d1682 Signed-off-by: Maciej Fijalkowski Reviewed-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260828164918.451364-1-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski

vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()

2026-08-30T21:19:59Z

vxlan_mdb_is_valid_source(), which validates MDBE_ATTR_SOURCE and every MDBE_ATTR_SRC_LIST member, accepts the all-zeros address. A source list is only accepted on a (*, G) entry, whose source is the all-zeros address, and for each member of the list an (S, G) entry is derived from it by substituting the source. Entries are keyed by a plain memcmp() of struct vxlan_mdb_entry_key, so if MDBE_ATTR_SOURCE is present and holds the all-zeros address and the source list holds it as well, the derived (S, G) key is byte-identical to the (*, G) key and resolves to the same entry. Omitting MDBE_ATTR_SOURCE is not equivalent, as the key is then left with a zero address family. vxlan_mdb_remote_src_del() removes the forwarding entry of a source before freeing the source entry: vxlan_mdb_remote_src_fwd_del(vxlan, group, remote, &ent->addr); vxlan_mdb_remote_src_entry_del(ent); With the keys aliased, the first call deletes the remote of the entry that owns 'ent' instead of a separate (S, G) entry, and frees 'ent'. The second call then runs on the freed entry, and its hlist_del() reads ->pprev and ->next out of it and writes through them. Adding the (*, G) entry with NLM_F_REPLACE and no source list marks the all-zeros source for deletion and reaches this from the sweep at the end of vxlan_mdb_remote_srcs_replace(). BUG: KASAN: slab-use-after-free in __vxlan_mdb_add+0x1cd/0xd70 Read of size 8 at addr ffff888102852500 by task poc/84 __vxlan_mdb_add+0x1cd/0xd70 vxlan_mdb_add+0xc0/0x140 rtnl_mdb_add+0x157/0x2a0 rtnetlink_rcv_msg+0x207/0x5a0 Allocated by task 84: __kmalloc_cache_noprof+0x153/0x360 vxlan_mdb_remote_srcs_add+0x2eb/0x440 __vxlan_mdb_add+0x803/0xd70 Freed by task 84: kfree+0x14c/0x3b0 vxlan_mdb_remote_del+0x129/0x1a0 __vxlan_mdb_del+0x4f/0xe0 vxlan_mdb_remote_src_fwd_del.isra.0+0x162/0x1b0 __vxlan_mdb_add+0x1c5/0xd70 The MDB operations are netns-scoped, so an unprivileged user can perform them in a new user and network namespace. Reject the all-zeros address in vxlan_mdb_is_valid_source(), which covers both call sites. A (*, G) entry is expressed by omitting the source, so nothing legitimate is refused. Discovered by XBOW, triaged by Baul Lee Fixes: a3a48de5eade ("vxlan: mdb: Add MDB control path support") Signed-off-by: Baul Lee Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260826173604.90158-1-baul.lee@xbow.com Signed-off-by: Jakub Kicinski

sctp: validate chunk length in the inqueue parser

2026-08-30T21:17:53Z

SCTP chunks always include a four-byte generic header, but sctp_inq_pop() currently accepts shorter declared lengths. A zero-length chunk leaves chunk_end at the current header. When ASCONF is covered by the association's SCTP-AUTH policy, sctp_assoc_bh_rcv() can continue before the state machine performs its normal chunk-length check. sctp_inq_pop() then returns the same malformed chunk repeatedly and the receive softirq can lock up. A remote SCTP peer can trigger this after establishing an association on a kernel built with CONFIG_IP_SCTP and configured with net.sctp.addip_enable=1 and net.sctp.auth_enable=1. The reproducer did not require application credentials, a shared SCTP AUTH key, or net.sctp.addip_noauth_enable=1. On commit f967455fb2a5 ("seg6: reset IP6CB after IPv6 decapsulation"), one zero-length ASCONF caused repeated watchdog soft-lockup reports in a two-vCPU KVM guest. All 3 pre-trigger health probes succeeded, while 36 of 37 post-trigger probes failed. With this change, all 37 post-trigger probes succeeded and no equivalent soft-lockup signature appeared. Reject chunks shorter than the generic SCTP header at the shared inqueue parser boundary. Mark the packet for discard before either caller can continue processing it, while preserving the four-byte generic minimum. Declared-length 1 through 4 controls and kernel-generated ASCONF traffic remained healthy. The patched sctp_hello selftest passed for IPv4 and IPv6. The complete private reproducer and validation evidence are available directly to maintainers on request. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Cc: stable@vger.kernel.org Signed-off-by: Charles Vosburgh Acked-by: Xin Long Link: https://patch.msgid.link/20260827-sctp-zero-chunk-inqueue-v2-1-2e7669c6a6cb@gmail.com Signed-off-by: Jakub Kicinski

net: amd-xgbe: discard rx packets with bad FCS

2026-08-30T21:17:19Z

amd-xgbe driver currently sets the MAC_RCR.DCRCC bit whenever RX is enabled. This disables hardware FCS validation, causing packets with bad FCS to be accepted unconditionally. This change unsets DCRCC so that packets with bad FCS will be dropped, in-line with typical behaviours of many other network controllers. Tests: - Verified that packets with bad FCS are now dropped. - Verified that receiving packets with bad FCS will increment the `rx_crc_errors` counter. Fixes: c5aa9e3b8156 ("amd-xgbe: Initial AMD 10GbE platform driver") Signed-off-by: James Nugraha Link: https://patch.msgid.link/20260827232220.69907-1-aslan.jnn@gmail.com Signed-off-by: Jakub Kicinski

raw: annotate disconnect-side IPv4 match writers

2026-08-30T21:14:57Z

raw_v4_match() reads inet_daddr, inet_rcv_saddr and sk_bound_dev_if locklessly under RCU. Bind and connect writers are annotated, but __udp_disconnect() still clears the same fields using plain stores. Commit 18f116931f52e ("raw: annotate lockless match fields in raw_v4_match()") added the lockless readers and annotated the raw bind and datagram connect writers. Its v4 revision intentionally left the shared disconnect-side IPv4 writers for follow-up cleanup. Complete that follow-up by using WRITE_ONCE() for the disconnect-side stores, including the inet_rcv_saddr reset in inet_reset_saddr(), to pair with the lockless raw socket matcher. Fixes: 0daf07e52709 ("raw: convert raw sockets to RCU") Link: https://lore.kernel.org/netdev/20260716142958.3064224-1-runyu.xiao@seu.edu.cn/ Suggested-by: Runyu Xiao Signed-off-by: Jackie Liu Signed-off-by: Xuanqiang Luo Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260828012918.1461-1-xuanqiang.luo@linux.dev Signed-off-by: Jakub Kicinski

sctp: fix soft lockup from unpadded ASCONF-ACK parameter iteration

2026-08-30T21:14:09Z

sctp_verify_asconf() walks ASCONF-ACK parameters with sctp_walk_params(), which advances by SCTP_PAD4(length), while the consumer sctp_get_asconf_response() iterates the same parameters advancing by the raw length, without padding. A single odd-length parameter desynchronises the two walks and makes the consumer interpret attacker-controlled bytes at a misaligned offset. When those bytes yield a length of zero, the while loop over asconf_ack_len makes no progress, spinning forever in softirq context, and the watchdog reports a soft lockup. All reads stay within the received skb, so the lockup is a pure remote denial of service. A remote peer can trigger it with a crafted ASCONF-ACK on an ADD-IP enabled association with an outstanding ASCONF (RFC 5061 section 4.1.2 requires the chunk to be authenticated, but the predefined empty key id 0 allows the peer to compute the same association HMAC from publicly exchanged parameters, so the gate does not help). The SCTP_PARAM_ERR_CAUSE case of sctp_verify_asconf() also performs no length check, letting a parameter without a complete error header reach the consumer, which reads errhdr.cause past the end of the parameter, an out-of-bounds read. Reject SCTP_PARAM_ERR_CAUSE parameters shorter than sizeof(struct sctp_addip_param) + sizeof(struct sctp_errhdr) at the verifier, and advance the consumer iterator with the same padding rule as the verifier to keep the two walks in lockstep. The verifier change guarantees a complete error header in every ERR_CAUSE parameter the consumer can see, so the consumer's asconf_ack_len check is dropped and it returns err_param->cause directly. The consumer padding fix is still required because odd lengths remain valid for SCTP_PARAM_ERR_CAUSE per RFC 5061. The issue was found by ZeroHive, a vulnerability hunting agent at Tencent Yunding Lab. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Henry Martin Acked-by: Xin Long Link: https://patch.msgid.link/20260828042431.3873725-1-bsdhenrymartin@gmail.com Signed-off-by: Jakub Kicinski

sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START

2026-08-28T23:09:25Z

The SCTP_CMD_TIMER_START handler checks timer_pending() before calling timer_reduce(). The timer can expire and detach between these operations, causing timer_reduce() to rearm the timer without taking the association reference required for the newly armed timer. The timer callback later unconditionally drops its association reference, which can leave the association reference count unbalanced and result in use-after-free during association teardown. Use the return value of timer_reduce() to determine whether the timer was actually armed. Take the association reference only when timer_reduce() successfully starts a new timer, closing the race between checking the timer state and rearming it. This issue was reported by Nico Yip (@_cyeaa_) working with TrendAI Zero Day Initiative. Fixes: 20a785aa52c8 ("sctp: Don't add the shutdown timer if its already been added") Reported-by: Zero Day Initiative Signed-off-by: Xin Long Link: https://patch.msgid.link/9d8f1b5c50329d5ea7c642128d35681abaa9ed20.1787773744.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski

Merge branch 'tcp-fix-use-after-free-in-do_tcp_getsockopt'

2026-08-28T23:09:04Z

Cen Zhang says: ==================== tcp: fix use-after-free in do_tcp_getsockopt() do_tcp_getsockopt() has two lockless reads of icsk_ca_ops. Since BPF struct_ops congestion control made icsk_ca_ops point to dynamically allocated memory, a concurrent setsockopt(TCP_CONGESTION) can replace the pointer and free the old object while either reader is using it. Patch 1 fixes the TCP_CONGESTION path by copying ca_ops->name to a stack buffer while holding rcu_read_lock(). It also uses READ_ONCE() for the lockless load and annotates the relevant icsk_ca_ops stores with WRITE_ONCE(). Patch 2 fixes the TCP_CC_INFO path by keeping the READ_ONCE() load, ca_ops->get_info lookup, and call inside an RCU read-side critical section. ==================== Link: https://patch.msgid.link/cover.1787870710.git.blbllhy@gmail.com Signed-off-by: Jakub Kicinski