kernel/linux.git/net/bridge, branch v5.10.259

net: bridge: use a stable FDB dst snapshot in RCU readers

2026-06-19T11:21:41+00:00

[ Upstream commit df4601653201de21b487c3e7fffd464790cab808 ] Local FDB entries can be rewritten in place by `fdb_delete_local()`, which updates `f->dst` to another port or to `NULL` while keeping the entry alive. Several bridge RCU readers inspect `f->dst`, including `br_fdb_fillbuf()` through the `brforward_read()` sysfs path. These readers currently load `f->dst` multiple times and can therefore observe inconsistent values across the check and later dereference. In `br_fdb_fillbuf()`, this means a concurrent local-FDB update can change `f->dst` after the NULL check and before the `port_no` dereference, leading to a NULL-ptr-deref. Fix this by taking a single `READ_ONCE()` snapshot of `f->dst` in each affected RCU reader and using that snapshot for the rest of the access sequence. Also publish the in-place `f->dst` updates in `fdb_delete_local()` with `WRITE_ONCE()` so the readers and writer use matching access patterns. Fixes: 960b589f86c7 ("bridge: Properly check if local fdb entry can be deleted in br_fdb_change_mac_address") Cc: stable@kernel.org Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Ren Wei Signed-off-by: Zhengchuan Liang Signed-off-by: Ren Wei Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/6570fabb85ecadb8baaf019efe856f407711c7b9.1776043229.git.zcliangcn@gmail.com Signed-off-by: Paolo Abeni [ kept combined `BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS` check and `cb->args[2]` instead of `br_is_neigh_suppress_enabled()` helper and `ctx->fdb_idx` ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfilter: bridge: make ebt_snat ARP rewrite writable

2026-06-19T11:21:34+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

netfilter: ebtables: fix OOB read in compat_mtw_from_user

2026-06-19T11:21:25+00:00

[ Upstream commit f438d1786d657d57790c5d138d6db3fc9fdac392 ] Luxiao Xu says: The function compat_mtw_from_user() converts ebtables extensions from 32-bit user structures to kernel native structures. However, it lacks proper validation of the user-supplied match_size/target_size. When certain extensions are processed, the kernel-side translation logic may perform memory accesses based on the extension's expected size. If the user provides a size smaller than what the extension requires, it results in an out-of-bounds read as reported by KASAN. This fix introduces a check to ensure match_size is at least as large as the extension's required compatsize. This covers matches, watchers, and targets, while maintaining compatibility with standard targets. AFAIU this is relevant for matches that need to go though match->compat_from_user() call. Those that use plain memcpy with the user-provided size are ok because the caller checks that size vs the start of the next rule entry offset (which itself is checked vs. total size copied from userspace). The ->compat_from_user() callbacks assume they can read compatsize bytes, so they need this extra check. Based on an earlier patch from Luxiao Xu. Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Reviewed-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

bridge: br_nd_send: validate ND option lengths

2026-04-18T08:31:12+00:00

commit 850837965af15707fd3142c1cf3c5bfaf022299b upstream. br_nd_send() walks ND options according to option-provided lengths. A malformed option can make the parser advance beyond the computed option span or use a too-short source LLADDR option payload. Validate option lengths against the remaining NS option area before advancing, and only read source LLADDR when the option is large enough for an Ethernet address. Fixes: ed842faeb2bd ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports") Cc: stable@vger.kernel.org Reported-by: Yifan Wu Reported-by: Juefei Pu Tested-by: Ao Zhou Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Signed-off-by: Yang Yang Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260326034441.2037420-3-n05ec@lzu.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

bridge: br_nd_send: linearize skb before parsing ND options

2026-04-18T08:31:08+00:00

[ Upstream commit a01aee7cafc575bb82f5529e8734e7052f9b16ea ] br_nd_send() parses neighbour discovery options from ns->opt[] and assumes that these options are in the linear part of request. Its callers only guarantee that the ICMPv6 header and target address are available, so the option area can still be non-linear. Parsing ns->opt[] in that case can access data past the linear buffer. Linearize request before option parsing and derive ns from the linear network header. Fixes: ed842faeb2bd ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports") Reported-by: Yifan Wu Reported-by: Juefei Pu Tested-by: Ao Zhou Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Signed-off-by: Yang Yang Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260326034441.2037420-2-n05ec@lzu.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

2026-04-18T08:30:52+00:00

[ Upstream commit e5e890630533bdc15b26a34bb8e7ef539bdf1322 ] When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neigh_lookup+0x16/0xe0 [...] Call Trace: ? neigh_lookup+0x16/0xe0 br_do_suppress_nd+0x160/0x290 [bridge] br_handle_frame_finish+0x500/0x620 [bridge] br_handle_frame+0x353/0x440 [bridge] __netif_receive_skb_core.constprop.0+0x298/0x1110 __netif_receive_skb_one_core+0x3d/0xa0 process_backlog+0xa0/0x140 __napi_poll+0x2c/0x170 net_rx_action+0x2c4/0x3a0 handle_softirqs+0xd0/0x270 do_softirq+0x3f/0x60 Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled. Fixes: ed842faeb2bd ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports") Reported-by: Guruprasad C P Closes: https://lore.kernel.org/netdev/CAHXs0ORzd62QOG-Fttqa2Cx_A_VFp=utE2H2VTX5nqfgs7LDxQ@mail.gmail.com/ Signed-off-by: Fernando Fernandez Mancera Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260304120357.9778-1-fmancera@suse.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: fix static key check

2026-02-06T15:40:11+00:00

[ Upstream commit cc0cf10fdaeadf5542d64a55b5b4120d3df90b7d ] Fix the check if netfilter's static keys are available. netfilter defines and exports static keys if CONFIG_JUMP_LABEL is enabled. (HAVE_JUMP_LABEL is never defined.) Fixes: 971502d77faa ("bridge: netfilter: unroll NF_HOOK helper in bridge input path") Signed-off-by: Martin Kaiser Reviewed-by: Florian Westphal Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260127101925.1754425-1-martin@kaiser.cx Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

bridge: fix C-VLAN preservation in 802.1ad vlan_tunnel egress

2026-01-19T12:12:10+00:00

[ Upstream commit 3128df6be147768fe536986fbb85db1d37806a9f ] When using an 802.1ad bridge with vlan_tunnel, the C-VLAN tag is incorrectly stripped from frames during egress processing. br_handle_egress_vlan_tunnel() uses skb_vlan_pop() to remove the S-VLAN from hwaccel before VXLAN encapsulation. However, skb_vlan_pop() also moves any "next" VLAN from the payload into hwaccel: /* move next vlan tag to hw accel tag */ __skb_vlan_pop(skb, &vlan_tci); __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci); For QinQ frames where the C-VLAN sits in the payload, this moves it to hwaccel where it gets lost during VXLAN encapsulation. Fix by calling __vlan_hwaccel_clear_tag() directly, which clears only the hwaccel S-VLAN and leaves the payload untouched. This path is only taken when vlan_tunnel is enabled and tunnel_info is configured, so 802.1Q bridges are unaffected. Tested with 802.1ad bridge + VXLAN vlan_tunnel, verified C-VLAN preserved in VXLAN payload via tcpdump. Fixes: 11538d039ac6 ("bridge: vlan dst_metadata hooks in ingress and egress paths") Signed-off-by: Alexandre Knecht Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20251228020057.2788865-1-knecht.alexandre@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: Describe @tunnel_hash member in net_bridge_vlan_group struct

2026-01-19T12:11:54+00:00

[ Upstream commit f79f9b7ace1713e4b83888c385f5f55519dfb687 ] Sphinx reports kernel-doc warning: WARNING: ./net/bridge/br_private.h:267 struct member 'tunnel_hash' not described in 'net_bridge_vlan_group' Fix it by describing @tunnel_hash member. Fixes: efa5356b0d9753 ("bridge: per vlan dst_metadata netlink support") Signed-off-by: Bagas Sanjaya Acked-by: Nikolay Aleksandrov Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20251218042936.24175-2-bagasdotme@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

bridge: Redirect to backup port when port is administratively down

2025-12-06T21:08:11+00:00

[ Upstream commit 3d05b24429e1de7a17c8fdccb04a04dbc8ad297b ] If a backup port is configured for a bridge port, the bridge will redirect known unicast traffic towards the backup port when the primary port is administratively up but without a carrier. This is useful, for example, in MLAG configurations where a system is connected to two switches and there is a peer link between both switches. The peer link serves as the backup port in case one of the switches loses its connection to the multi-homed system. In order to avoid flooding when the primary port loses its carrier, the bridge does not flush dynamic FDB entries pointing to the port upon STP disablement, if the port has a backup port. The above means that known unicast traffic destined to the primary port will be blackholed when the port is put administratively down, until the FDB entries pointing to it are aged-out. Given that the current behavior is quite weird and unlikely to be depended on by anyone, amend the bridge to redirect to the backup port also when the primary port is administratively down and not only when it does not have a carrier. The change is motivated by a report from a user who expected traffic to be redirected to the backup port when the primary port was put administratively down while debugging a network issue. Reviewed-by: Petr Machata Signed-off-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20250812080213.325298-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin