laptop-kernel/net/openvswitch, branch master

net: openvswitch: validate transport header presence in set_ipv6_addr

2026-10-08T18:33:38Z

When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header(). update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless. Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing. See the syzbot trace: !skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline] RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline] RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399 [...] Call Trace: set_ipv6 net/openvswitch/actions.c:531 [inline] do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366 ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592 ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 Reported-by: syzbot+4cc63fcfb3845e149969@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=4cc63fcfb3845e149969 Fixes: 3fdbd1ce11e5 ("openvswitch: add ipv6 'set' action") Signed-off-by: Fernando Fernandez Mancera Reviewed-by: Ilya Maximets Link: https://patch.msgid.link/20261008104135.4722-1-fmancera@suse.de Signed-off-by: Jakub Kicinski

openvswitch: fix soft lockup in the netlink flow dump

2026-10-05T02:51:13Z

A production compute node carrying a few thousand datapath flows hit a soft lockup inside a single netlink flow dump and panicked. ovs_flow_cmd_dump() calls ovs_flow_stats_get() for every flow it emits, and that releases stats->lock with spin_unlock_bh() once per CPU that has touched the flow. Every release is a local_bh_enable(), and each one runs the pending softirq backlog in the dumping thread's own context. The skb bounds the flows one callback emits, but not the softirq work it absorbs. On a CPU that carries the box's packet load the backlog refills as fast as it drains, so the dumping thread becomes that CPU's softirq engine. It never sleeps and it has no reschedule point, so under voluntary preemption nothing can take the CPU away from it: neither the ksoftirqd the kernel woke to take the work over, nor the stopper thread the softlockup detector dispatches to refresh its timestamp. Hold BH off across the whole callback instead, the way ctnetlink_dump_table() does, so the nested spin_unlock_bh() stop draining softirqs. The loop already runs under rcu_read_lock() and cannot sleep. What it gives up is preemption under CONFIG_PREEMPT, since a BH-off region is not preemptible outside PREEMPT_RT. The region stays short: the skb caps the flows one callback emits, and empty buckets cost no skb space but are each visited once per dump, as the cursor only moves forward. The table grows on insert and shrinks only on flush, so the walk is bounded by the largest flow count the datapath has held. The softirq backlog the callback used to absorb has no bound at all. Fixes: 63e7959c4b9b ("openvswitch: Per NUMA node flow stats.") Cc: stable@vger.kernel.org Signed-off-by: Denis V. Lunev Reviewed-by: Ilya Maximets Signed-off-by: David S. Miller

net: openvswitch: conntrack: fix helper UAF due to extensions realloc

2026-09-24T16:56:01Z

While calling the helpers, a raw pointer to the extensions area is wired into expectations list: -> nf_ct_helper() -> helper->help() -> nf_ct_expect_related_report() -> nf_ct_expect_insert() -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations) In case the connection is not confirmed yet, more extensions can be added afterwards with *_ext_add() calls reallocating the extension space and leaving the now invalid pointer in the expectations list that is later accessed while removing the expectation. Make sure that helpers are called at the end after all the other extensions are already added. Note that the helper rejection now leaves the mark and labels set, but that's not different from how the NAT was handled before or how the mark and the labels were handled on confirmation failure. And there are no atomicity guarantees provided by the API anyway. Fixes: cae3a2627520 ("openvswitch: Allow attaching helpers to ct action") Cc: stable@vger.kernel.org Reported-by: Axel Mierczuk Signed-off-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20260921145655.3167436-4-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

net: openvswitch: conntrack: remove 'add_helper' dead code

2026-09-24T16:56:01Z

This variable can only become 'true' when the connection is not confirmed, but it is only checked when it is confirmed. So, it can be treated as being always false and just removed. Fixes: 3c1860543fcc ("openvswitch: add nf_ct_is_confirmed check before assigning the helper") Cc: stable@vger.kernel.org Signed-off-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20260921145655.3167436-3-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry

2026-09-24T16:56:01Z

In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing. Fixes: cae3a2627520 ("openvswitch: Allow attaching helpers to ct action") Cc: stable@vger.kernel.org Reported-by: Axel Mierczuk Signed-off-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20260921145655.3167436-2-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

openvswitch: avoid reallocating confirmed conntrack labels

2026-09-16T01:00:46Z

ovs_ct_get_conn_labels() adds the labels extension when a conntrack entry does not have one. Confirmed conntracks can be read locklessly, so adding an extension may reallocate and free the extension block while another CPU accesses it. Only add the extension for unconfirmed conntracks. A confirmed conntrack without labels now fails the caller's label operation instead of reallocating its extension storage. Fixes: c2ac66735870 ("openvswitch: Allow matching on conntrack label") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Reviewed-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/372fbb062b40ae6723684f55484be86ff0064f8e.1789218015.git.zhilinz@nebusec.ai Signed-off-by: Jakub Kicinski

openvswitch: fix wrong flag value in get_ipv6_ext_hdrs()

2026-09-10T15:51:30Z

The ESP and AH cases in get_ipv6_ext_hdrs() used IPPROTO_FRAGMENT instead of OFPIEH12_FRAG when checking for out-of-order extension headers, causing the fragment header to not be recognised as a valid predecessor. The original code used IPPROTO_FRAGMENT (44) as a bitmask constant where OFPIEH12_FRAG (1 << 4 = 16) was intended. IPPROTO_FRAGMENT encodes bits 2, 3 and 5 (OFPIEH12_AUTH | OFPIEH12_DEST | OFPIEH12_ROUTER), but not bit 4 (OFPIEH12_FRAG). This caused incorrect OFPIEH12_UNSEQ verdicts in both the ESP and AH arms: the ESP arm failed to whitelist OFPIEH12_FRAG, while the AH arm accidentally whitelisted OFPIEH12_AUTH. With the fix, a packet with two AH headers now also gets OFPIEH12_UNSEQ in addition to OFPIEH12_UNREP, matching the ESP arm which already sets UNSEQ on a repeat, which is the intended behavior. Fixes: 28a3f0601727 ("net: openvswitch: IPv6: Add IPv6 extension header support") Reported-by: Paolo Abeni Reviewed-by: Aaron Conole Reviewed-by: Ilya Maximets Signed-off-by: Eelco Chaudron Link: https://patch.msgid.link/1b1582eb07550d71f3cbe210e5cb31eeb8d0ad86.1788876917.git.echaudro@redhat.com Signed-off-by: Jakub Kicinski

net: openvswitch: fix use-after-free of the flow table mask array

2026-09-09T00:24:10Z

tbl_mask_array_realloc() retires the old mask_array before it stops being reachable: old = ovsl_dereference(tbl->mask_array); if (old) { ... call_rcu(&old->rcu, mask_array_rcu_cb); } rcu_assign_pointer(tbl->mask_array, new); call_rcu() only waits for read-side critical sections already in flight. tbl->mask_array still points at old between the call_rcu() and the rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in that window picks up old in a fresh critical section that the pending grace period does not cover. tbl_mask_array_realloc() runs in process context under ovs_mutex, so the window is preemptible and can outlast the grace period. Then mask_array_rcu_cb() frees old before the swap runs: BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0 Read of size 8 at addr ffff888020b3e018 by task poc/741 flow_lookup.constprop.0+0x2bf/0x2f0 ovs_flow_tbl_lookup_stats+0x4a3/0x5c0 ovs_dp_process_packet+0x19c/0x710 ovs_vport_receive+0x243/0x390 internal_dev_xmit+0x81/0x170 Freed by task 728: kfree+0x16a/0x4e0 rcu_core+0x853/0x1030 Publish the new array before retiring the old one. The kfree_rcu() that call_rcu() replaced ran after the swap. Fixes: eac87c413bf9 ("net: openvswitch: reorder masks array based on usage") Cc: stable@vger.kernel.org Signed-off-by: Norbert Szetei Reviewed-by: Ilya Maximets Acked-by: Eelco Chaudron echaudro@redhat.com Link: https://patch.msgid.link/DE115F9C-2545-423E-A702-986FC952FD62@doyensec.com Signed-off-by: Jakub Kicinski

openvswitch: only skb_tx_error() a packet we are about to drop

2026-08-25T07:36:47Z

queue_userspace_packet() borrows the packet skb -- it only copies it into a private netlink message (user_skb) and does not own it; on return do_execute_actions() keeps forwarding it through the flow's remaining actions. Its error path nevertheless calls skb_tx_error(skb), which via skb_zcopy_clear() does skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY, stripping SKBFL_SHARED_FRAG from that live skb (skb_tx_error()'s kerneldoc says "skb must be freed afterwards"). For a MSG_ZEROCOPY skb carrying page-cache frags, SKBFL_SHARED_FRAG is what makes esp_input() skb_cow_data() before in-place AEAD; once it is stripped a later local ESP-in-UDP delivery decrypts in place over pages the sender does not own -- an unprivileged page-cache write (the "Fragnesia" primitive). do_execute_actions() ignores output_userspace()'s return value, so any action after a failed USERSPACE upcall inherits the stripped skb. Move the skb_tx_error() to the flow-miss drop path - the "default" branch of ovs_dp_process_packet()'s switch(error), before kfree_skb(). The call has been here since commit 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors") but was harmless until esp_input() began relying on SKBFL_SHARED_FRAG to gate in-place decrypt; only then did stripping it on a still-forwarded skb become a page-cache write primitive. Fixes: 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors") Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-5 Signed-off-by: Norbert Szetei Reviewed-by: Ilya Maximets Tested-by: Jongmin Jang Link: https://patch.msgid.link/55A52703-7548-4A55-A9CE-2A37145BDCAD@doyensec.com Signed-off-by: Paolo Abeni

openvswitch: Fix CT limit teardown use-after-free

2026-08-24T18:38:09Z

Packet processing uses CT limit state under RCU, while netns teardown frees that state under ovs_mutex. The CT limit pointer was neither removed from readers nor protected by a grace period, allowing packet processing to dereference the freed state. An unprivileged user can trigger this bug from a user and network namespace, causing a slab-use-after-free in ovs_ct_execute() when the netns is torn down. Publish the CT limit pointer through RCU, remove it before teardown, and wait for readers before freeing its contents. Keep ovs_mutex around individual CT limit updates, and use the RCU read-side lock while GET traverses the RCU-protected limit lists. Netns teardown detaches the RCU-protected CT limit state in the pernet .pre_exit callback while holding ovs_mutex. The pernet core guarantees an RCU grace period between the .pre_exit and .exit callbacks, so the .exit callback completes the teardown without adding any extra synchronization. The netlink command handlers do not need NULL checks because the userspace netlink socket holds an active reference to its network namespace while a request is processed. The per-netns exit path therefore cannot run concurrently with SET, DEL, or GET for that socket's namespace. Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit") Cc: stable@vger.kernel.org Reported-by: Vega Link: https://lore.kernel.org/all/cover.1784711445.git.xuyuqiabc@gmail.com Co-developed-by: Nan Li Signed-off-by: Nan Li Signed-off-by: Yuqi Xu Reviewed-by: Ren Wei Reviewed-by: Ilya Maximets Link: https://patch.msgid.link/288fbd5459d92b9dd0dcc6faf625f04819161ff3.1787280296.git.xuyuqiabc@gmail.com Signed-off-by: Jakub Kicinski