wireguard-linux/net/xfrm, branch stable

xfrm: input: hold netns during deferred transport reinjection

2026-05-26T08:35:30Z

Transport-mode reinjection stores a struct net pointer in skb->cb and uses it later from xfrm_trans_reinject(). That pointer must stay valid until the deferred callback runs. Take a netns reference when queueing deferred reinjection work and drop it after the callback completes. Use maybe_get_net() so the queueing path does not revive a namespace that is already being torn down. This keeps the existing workqueue design and fixes the netns lifetime handling in one place for all users of xfrm_trans_queue_net(). Fixes: 7b3801927e52 ("xfrm: introduce xfrm_trans_queue_net") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Xin Liu Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zhengchuan Liang Signed-off-by: Ren Wei Assisted-by: Codex:gpt-5.4 Signed-off-by: Steffen Klassert

xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit

2026-05-26T08:35:29Z

The struct pernet_operations docstring in include/net/net_namespace.h explicitly warns against blocking RCU primitives in .exit handlers: Exit methods using blocking RCU primitives, such as synchronize_rcu(), should be implemented via exit_batch. [...] Please, avoid synchronize_rcu() at all, where it's possible. Note that a combination of pre_exit() and exit() can be used, since a synchronize_rcu() is guaranteed between the calls. xfrm_policy_fini() violates this: it calls synchronize_rcu() before freeing the policy_bydst hash tables (so no RCU reader is mid- traversal at free time), but runs from xfrm_net_ops.exit -- once per namespace -- so a cleanup_net() of N namespaces pays N full RCU grace periods serially. Use the documented pre_exit/exit split. Move the policy flush (and the workqueue drains it depends on) into a new .pre_exit handler; xfrm_policy_fini() then runs in .exit and frees the hash tables after the synchronize_rcu_expedited() that cleanup_net() guarantees between the two phases. Providing O(1) RCU grace periods per batch instead of O(N). Observed on Linux 6.18 with a workload doing unshare(CLONE_NEWNET) at ~13/sec sustained: cleanup_net() and the netns_wq rescuer kthread both stuck in xfrm_policy_fini()'s synchronize_rcu(), >300k struct net accumulated in the cleanup queue, Percpu in /proc/meminfo climbed to 130+ GB on 256-CPU hosts, and memcg OOMs followed. setup_net and __put_net counts were balanced, ruling out a refcount leak. Fixes: 069daad4f2ae ("xfrm: Wait for RCU readers during policy netns exit") Signed-off-by: Usama Arif Signed-off-by: Steffen Klassert

xfrm: iptfs: reset runtime state when cloning SAs

2026-05-26T08:35:28Z

iptfs_clone_state() clones the IPTFS mode data with kmemdup(). This copies runtime objects which must not be shared with the original SA, including the embedded sk_buff_head, hrtimers, spinlock, and in-flight reassembly/reorder state. If xfrm_state_migrate() fails after clone_state() but before the later init_state() call has reinitialized those fields, the cloned state can be destroyed by xfrm_state_gc_task() with list and timer state copied from the original SA. With queued packets this lets the clone splice and free skbs owned by the original IPTFS queue, leading to use-after-free and double-free reports in iptfs_destroy_state() and skb release paths. Reinitialize the clone's runtime state before publishing it through x->mode_data. Because clone_state() now publishes a destroyable mode_data object before init_state(), take the mode callback module reference there. Avoid taking it again from __iptfs_init_state() for the same object. Fixes: 0e4fbf013fa5 ("xfrm: iptfs: add user packet (tunnel ingress) handling") Cc: stable@vger.kernel.org Signed-off-by: Shaomin Chen Signed-off-by: Steffen Klassert

xfrm: Check for underflow in xfrm_state_mtu

2026-05-14T08:17:43Z

Leo Lin reported OOB write issue in esp component: xfrm_state_mtu() returns u32 but performs its arithmetic in unsigned modulo-2^32 space using an attacker-influenced "header_len + authsize + net_adj" subtracted from a small "mtu" argument. A nobody user can install an IPv4 ESP tunnel SA with a large authentication key (XFRMA_ALG_AUTH_TRUNC, e.g. hmac(sha512), 64-byte key, 64-byte trunc), configure a small interface MTU (68 bytes), and set XFRMA_TFCPAD to a large value. When a single UDP datagram is then sent through the tunnel, xfrm_state_mtu() underflows to a near-2^32 value, and esp_output() consumes it as a signed int via: padto = min(x->tfcpad, xfrm_state_mtu(x, mtu_cached)) esp.tfclen = padto - skb->len (assigned to int) esp.tfclen ends up negative (e.g. -207). It is sign-extended to size_t when passed to memset() inside esp_output_fill_trailer(), producing a ~16 EB write of zeroes at skb_tail_pointer(skb). KASAN logs it as "Write of size 18446744073709551537 at addr ffff888...". Check for underflow and return 1. This causes the sendmsg attempt to fail with ENETUNREACH. Fixes: c5c252389374 ("[XFRM]: Optimize MTU calculation") Reported-by: Leo Lin Assisted-by: Codex:26.506.31004 Signed-off-by: David Ahern Signed-off-by: Steffen Klassert

xfrm: ipcomp: Free destination pages on acomp errors

2026-05-11T08:34:35Z

Move the out_free_req label up by a couple of lines so that the allocated dst SG list gets freed on error as well as success. Fixes: eb2953d26971 ("xfrm: ipcomp: Use crypto_acomp interface") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Reported-by: Yilin Zhu Signed-off-by: Herbert Xu Signed-off-by: Steffen Klassert

xfrm: route MIGRATE notifications to caller's netns

2026-05-07T07:31:10Z

xfrm_send_migrate() in net/xfrm/xfrm_user.c and pfkey_send_migrate() in net/key/af_key.c both hardcode &init_net for the multicast that announces a successful XFRM_MSG_MIGRATE / SADB_X_MIGRATE. XFRM_MSG_MIGRATE arrives on a per-netns NETLINK_XFRM socket, and the rest of the xfrm/af_key netlink path was made netns-aware in 2008. The other 14 multicast paths in xfrm_user.c route their event using xs_net(x), xp_net(xp) or sock_net(skb->sk); only the migrate path was missed. Two consequences of the init_net hardcoding: 1. The notification (selector, old/new endpoint addresses, and the km_address) is delivered to listeners on init_net's XFRMNLGRP_MIGRATE / pfkey BROADCAST_ALL groups rather than on the issuing netns. An IKE daemon running in init_net therefore receives migration notifications originating from any other netns on the host. 2. An IKE daemon running inside a non-init netns and subscribed to its own XFRMNLGRP_MIGRATE / pfkey groups never receives the notification of its own migration. IKEv2 MOBIKE / address-update handling inside a netns is silently broken. Thread struct net through km_migrate() and the xfrm_mgr.migrate function pointer, drop the &init_net override in xfrm_send_migrate() and pfkey_send_migrate(), and pass the caller's net (already in scope in xfrm_migrate() via sock_net(skb->sk)) all the way down. struct xfrm_mgr is in-tree only and not exported as a stable API, so the function-pointer signature change is internal. pfkey_broadcast() is already netns-aware via net_generic(net, pfkey_net_id) since the pernet conversion. The five other pfkey_broadcast() callers in af_key.c already pass xs_net(x), sock_net(sk) or a per-netns net, so this only removes the &init_net outlier. Fixes: 5c79de6e79cd ("[XFRM]: User interface for handling XFRM_MSG_MIGRATE") Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Maoyi Xie Signed-off-by: Steffen Klassert

xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete

2026-04-29T09:27:34Z

KASAN reproduces a slab-use-after-free in __xfrm_state_delete()'s hlist_del_rcu calls under syzkaller load on linux-6.12.y stable (reproduced on 6.12.47, also reachable via the same code path on torvalds/master and on the ipsec tree). Nine unique signatures cluster in the xfrm_state lifecycle, the load-bearing one being: BUG: KASAN: slab-use-after-free in __hlist_del include/linux/list.h:990 [inline] BUG: KASAN: slab-use-after-free in hlist_del_rcu include/linux/rculist.h:516 [inline] BUG: KASAN: slab-use-after-free in __xfrm_state_delete net/xfrm/xfrm_state.c Write of size 8 at addr ffff8881198bcb70 by task kworker/u8:9/435 Workqueue: netns cleanup_net Call Trace: __hlist_del / hlist_del_rcu __xfrm_state_delete xfrm_state_delete xfrm_state_flush xfrm_state_fini ops_exit_list cleanup_net The other observed signatures hit the same slab object from __xfrm_state_lookup, xfrm_alloc_spi, __xfrm_state_insert and an OOB write variant of __xfrm_state_delete, all on the byseq/byspi hash chains. __xfrm_state_delete() guards its byseq and byspi unhashes with value-based predicates: if (x->km.seq) hlist_del_rcu(&x->byseq); if (x->id.spi) hlist_del_rcu(&x->byspi); while everywhere else in the file (e.g. state_cache, state_cache_input) the safer hlist_unhashed() check is used. xfrm_alloc_spi() sets x->id.spi = newspi inside xfrm_state_lock and then immediately inserts into byspi, but a path that observes x->id.spi != 0 outside of xfrm_state_lock can still skip-or-hit the byspi unhash inconsistently with whether x is actually on the list. The same holds for x->km.seq versus byseq, and the bydst/bysrc unhashes have no predicate at all, so a second __xfrm_state_delete() on the same object writes through LIST_POISON pprev. The defensive change here: - Use hlist_del_init_rcu() instead of hlist_del_rcu() on bydst, bysrc, byseq and byspi so a second deletion is a no-op rather than a write through LIST_POISON pprev. The byseq/byspi nodes are already initialised in xfrm_state_alloc(). - Test hlist_unhashed() rather than the value predicate for byseq/byspi, so the unhash decision tracks list state rather than mutable scalar fields. Empirical verification: applied this patch on top of v6.12.47, rebuilt, and re-ran the same syzkaller harness for 1h16m on a previously-crashy configuration that produced ~100 hits each of slab-use-after-free Read in xfrm_alloc_spi / Read in __xfrm_state_lookup / Write in __xfrm_state_delete. After the patch, 7.1M execs across 32 VMs at ~1550 exec/sec produced zero xfrm_state UAF/OOB hits. /proc/slabinfo confirms the xfrm_state slab is actively allocated and freed during the run (~143 KiB resident), so the fuzzer is still exercising those code paths -- they just no longer crash. Reproduction: - Linux 6.12.47 x86_64 + KASAN_GENERIC + KASAN_INLINE + KCOV - syzkaller @ 746545b8b1e4c3a128db8652b340d3df90ce61db - 32 QEMU/KVM VMs x 2 vCPU on AWS c5.metal bare metal - 9 unique signatures collected in ~9h, all within xfrm_state lifecycle Fixes: fe9f1d8779cb ("xfrm: add state hashtable keyed by seq") Fixes: 7b4dc3600e48 ("[XFRM]: Do not add a state whose SPI is zero to the SPI hash.") Reported-by: Michal Kosiorek Tested-by: Michal Kosiorek Cc: stable@vger.kernel.org Signed-off-by: Michal Kosiorek Signed-off-by: Steffen Klassert

xfrm: provide message size for XFRM_MSG_MAPPING

2026-04-29T07:10:25Z

The compat 64=>32 translation path handles XFRM_MSG_MAPPING, but xfrm_msg_min[] does not provide the native payload size for this message type. Add the missing XFRM_MSG_MAPPING entry so compat translation can size and translate mapping notifications correctly. Fixes: 5461fc0c8d9f ("xfrm/compat: Add 64=>32-bit messages translator") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruijie Li Signed-off-by: Ren Wei Signed-off-by: Steffen Klassert

xfrm: Don't clobber inner headers when already set

2026-04-28T04:47:20Z

On VXLAN over IPsec egress, xfrm{4,6}_transport_output() blindly overwrite inner_transport_header (== the inner TCP header saved in VXLAN iptunnel_handle_offloads() -> skb_reset_inner_headers()) with the current transport_header (== the VXLAN outer UDP header set by udp_tunnel_xmit_skb()). This was a latent bug, harmless until commit [1] added a doff validation check in qdisc_pkt_len_segs_init() for encapsulated GSO packets. With the wrong inner_transport_header set by xfrm, qdisc_pkt_len_segs_init() interprets inner_transport_header as a TCP header, reads doff=0 from the upper byte of the VNI and drops the packet with DROP_REASON_SKB_BAD_GSO. Besides the use in GSO to determine the header size of segmented packets, inner_transport_header might be used by drivers to set up inner checksum offloading by pointing the HW to the inner transport header. A quick browse through available drivers shows that mlx5 uses skb->csum_start specifically for this scenario, while others either don't support VXLAN over IPsec crypto offload (ixgbe) or the HW is capable of parsing the packets itself (nfp, Chelsio). But in all cases, it is more correct to let the inner_transport_header point to the innermost header instead of overwriting it in xfrm. So fix this by guarding all four inner header save sites in xfrm_output.c (xfrm{4,6}_transport_output, xfrm{4,6}_tunnel_encap_add) with a check for skb->inner_protocol. When inner_protocol is set, a tunnel layer (VXLAN, Geneve, GRE, etc.) has already saved the correct inner header offsets and they must not be overwritten. When inner_protocol is zero, no prior tunnel encapsulation exists and xfrm must save the inner headers itself. The tunnel mode checks are only added for completion, since they aren't strictly required, as xfrm_output() forces software GSO in tunnel mode before encap. This makes the previously added test pass: # ./tools/testing/selftests/drivers/net/hw/ipsec_vxlan.py TAP version 13 1..4 ok 1 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v4_inner_v4 ok 2 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v4_inner_v6 ok 3 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v6_inner_v4 ok 4 ipsec_vxlan.test_vxlan_ipsec_crypto_offload.outer_v6_inner_v6 # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0 [1] commit 7fb4c1967011 ("net: pull headers in qdisc_pkt_len_segs_init()") Fixes: f1bd7d659ef0 ("xfrm: Add encapsulation header offsets while SKB is not encrypted") Signed-off-by: Cosmin Ratiu Signed-off-by: Steffen Klassert

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-04-09T20:20:59Z

Cross-merge networking fixes after downstream PR (net-7.0-rc8). Conflicts: net/ipv6/seg6_iptunnel.c c3812651b522f ("seg6: separate dst_cache for input and output paths in seg6 lwtunnel") 78723a62b969a ("seg6: add per-route tunnel source address") https://lore.kernel.org/adZhwtOYfo-0ImSa@sirena.org.uk net/ipv4/icmp.c fde29fd934932 ("ipv4: icmp: fix null-ptr-deref in icmp_build_probe()") d98adfbdd5c01 ("ipv4: drop ipv6_stub usage and use direct function calls") https://lore.kernel.org/adO3dccqnr6j-BL9@sirena.org.uk Adjacent changes: drivers/net/ethernet/stmicro/stmmac/chain_mode.c 51f4e090b9f8 ("net: stmmac: fix integer underflow in chain mode") 6b4286e05508 ("net: stmmac: rename STMMAC_GET_ENTRY() -> STMMAC_NEXT_ENTRY()") Signed-off-by: Jakub Kicinski