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Sat, 28 Feb 2026 09:46:50 -0800 (PST) From: =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= Date: Sat, 28 Feb 2026 14:46:26 -0300 Subject: [PATCH net 1/3] bpf: bpf_out_neigh_v4: Fix nd_tbl NULL dereference when IPv6 is disabled Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260228-net-nd_tbl_fixes-v1-1-2b2a274df9bb@suse.com> References: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> In-Reply-To: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> To: Martin KaFai Lau , Daniel Borkmann , John Fastabend , Stanislav Fomichev , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , David Ahern , Jay Vosburgh , Andrew Lunn , Hangbin Liu Cc: Fernando Fernandez Mancera , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openssh-sha256; t=1772300803; l=2182; i=rbm@suse.com; h=from:subject:message-id; bh=ucFGNhQbyvRgliJm2iclmlbV7LXFrBb9Ujgx98X8vXQ=; b=U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgguRCc5X8/UX9M40lkMnr//aFGOhce x5ezt8MFNUFlqYAAAAGcGF0YXR0AAAAAAAAAAZzaGE1MTIAAABTAAAAC3NzaC1lZDI1NTE5AAAA QLqZmcEzlqILSWD7UP8bPCY/O1xURrrkYnEZviyYV9TEw84KCTDDT97+pGEpf5s2Sx5NOTFb0HA dNu1zqk+zRwU= X-Developer-Key: i=rbm@suse.com; a=openssh; fpr=SHA256:pzhe0fJpYLz+3cZ33FFPhIfaUElk9CXPFFXmalIH+1g When booting with the 'ipv6.disable=3D1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. If bpf_redirect_neigh() is called from tc with an explicit nexthop of nh_family =3D=3D AF_INET6, bpf_out_neigh_v4() takes the AF_INET6 branch and calls ip_neigh_gw6(), which relies on ipv6_stub->nd_tbl. BUG: kernel NULL pointer dereference, address: 0000000000000248 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:skb_do_redirect+0xb93/0xf00 Call Trace: ? srso_alias_return_thunk+0x5/0xfbef5 ? __tcf_classify.constprop.0+0x83/0x160 ? srso_alias_return_thunk+0x5/0xfbef5 ? tcf_classify+0x2b/0x50 ? srso_alias_return_thunk+0x5/0xfbef5 ? tc_run+0xb8/0x120 ? srso_alias_return_thunk+0x5/0xfbef5 __dev_queue_xmit+0x6fa/0x1000 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? alloc_skb_with_frags+0x58/0x200 packet_sendmsg+0x10da/0x1700 ? srso_alias_return_thunk+0x5/0xfbef5 __sys_sendto+0x1f3/0x220 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x101/0xf80 ? exc_page_fault+0x6e/0x170 ? srso_alias_return_thunk+0x5/0xfbef5 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by adding an early check in the AF_INET6 branch of bpf_out_neigh_v4(). If ipv6_stub->nd_tbl is NULL, unlock RCU and drop the packet. Suggested-by: Fernando Fernandez Mancera Fixes: ba452c9e996d ("bpf: Fix bpf_redirect_neigh helper api to support sup= plying nexthop") Signed-off-by: Ricardo B. Marli=C3=A8re --- net/core/filter.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 0d5d5a17acb2..9ab2fae3a0d9 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2335,6 +2335,10 @@ static int bpf_out_neigh_v4(struct net *net, struct = sk_buff *skb, =20 neigh =3D ip_neigh_for_gw(rt, skb, &is_v6gw); } else if (nh->nh_family =3D=3D AF_INET6) { + if (!ipv6_stub->nd_tbl) { + rcu_read_unlock(); + goto out_drop; + } neigh =3D ip_neigh_gw6(dev, &nh->ipv6_nh); is_v6gw =3D true; } else if (nh->nh_family =3D=3D AF_INET) { --=20 2.53.0 From nobody Sat Apr 18 09:18:59 2026 Received: from mail-wm1-f52.google.com (mail-wm1-f52.google.com [209.85.128.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6C5942F57D for ; Sat, 28 Feb 2026 17:46:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.52 ARC-Seal: i=1; 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Sat, 28 Feb 2026 09:46:58 -0800 (PST) Received: from localhost ([189.99.238.12]) by smtp.gmail.com with ESMTPSA id a1e0cc1a2514c-94df65782f4sm7474139241.11.2026.02.28.09.46.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Feb 2026 09:46:57 -0800 (PST) From: =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= Date: Sat, 28 Feb 2026 14:46:27 -0300 Subject: [PATCH net 2/3] bpf: bpf_out_neigh_v6: Fix nd_tbl NULL dereference when IPv6 is disabled Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260228-net-nd_tbl_fixes-v1-2-2b2a274df9bb@suse.com> References: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> In-Reply-To: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> To: Martin KaFai Lau , Daniel Borkmann , John Fastabend , Stanislav Fomichev , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , David Ahern , Jay Vosburgh , Andrew Lunn , Hangbin Liu Cc: Fernando Fernandez Mancera , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openssh-sha256; t=1772300803; l=1989; i=rbm@suse.com; h=from:subject:message-id; bh=C4KUZeK1Hi7rfQcTxVhmRP3plJWRRKSRXeRWRjZLG2E=; b=U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgguRCc5X8/UX9M40lkMnr//aFGOhce x5ezt8MFNUFlqYAAAAGcGF0YXR0AAAAAAAAAAZzaGE1MTIAAABTAAAAC3NzaC1lZDI1NTE5AAAA QATSOt0MBqXmmfLN1fQuQPIpcZOIRw0awhFQgAxRXUZGNukQbfeMMEZkMUFe6uV+SU1Bf5CQenM 12cyI8o7mnAQ= X-Developer-Key: i=rbm@suse.com; a=openssh; fpr=SHA256:pzhe0fJpYLz+3cZ33FFPhIfaUElk9CXPFFXmalIH+1g When booting with the 'ipv6.disable=3D1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. If bpf_redirect_neigh() is called with explicit AF_INET6 nexthop parameters, __bpf_redirect_neigh_v6() can skip the IPv6 FIB lookup and call bpf_out_neigh_v6() directly. bpf_out_neigh_v6() then calls ip_neigh_gw6(), which uses ipv6_stub->nd_tbl. BUG: kernel NULL pointer dereference, address: 0000000000000248 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:skb_do_redirect+0x44f/0xf40 Call Trace: ? srso_alias_return_thunk+0x5/0xfbef5 ? __tcf_classify.constprop.0+0x83/0x160 ? srso_alias_return_thunk+0x5/0xfbef5 ? tcf_classify+0x2b/0x50 ? srso_alias_return_thunk+0x5/0xfbef5 ? tc_run+0xb8/0x120 ? srso_alias_return_thunk+0x5/0xfbef5 __dev_queue_xmit+0x6fa/0x1000 ? srso_alias_return_thunk+0x5/0xfbef5 packet_sendmsg+0x10da/0x1700 ? srso_alias_return_thunk+0x5/0xfbef5 __sys_sendto+0x1f3/0x220 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x101/0xf80 ? exc_page_fault+0x6e/0x170 ? srso_alias_return_thunk+0x5/0xfbef5 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by adding an early check in bpf_out_neigh_v6(). If ipv6_stub->nd_tbl is NULL, drop the packet before neighbor lookup. Suggested-by: Fernando Fernandez Mancera Fixes: ba452c9e996d ("bpf: Fix bpf_redirect_neigh helper api to support sup= plying nexthop") Signed-off-by: Ricardo B. 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Sat, 28 Feb 2026 09:47:02 -0800 (PST) Received: from localhost ([189.99.238.12]) by smtp.gmail.com with ESMTPSA id ada2fe7eead31-5ff1e845aabsm8703044137.7.2026.02.28.09.46.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Feb 2026 09:47:02 -0800 (PST) From: =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= Date: Sat, 28 Feb 2026 14:46:28 -0300 Subject: [PATCH net 3/3] net: bonding: Fix nd_tbl NULL dereference when IPv6 is disabled Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260228-net-nd_tbl_fixes-v1-3-2b2a274df9bb@suse.com> References: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> In-Reply-To: <20260228-net-nd_tbl_fixes-v1-0-2b2a274df9bb@suse.com> To: Martin KaFai Lau , Daniel Borkmann , John Fastabend , Stanislav Fomichev , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , David Ahern , Jay Vosburgh , Andrew Lunn , Hangbin Liu Cc: Fernando Fernandez Mancera , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openssh-sha256; t=1772300803; l=2807; i=rbm@suse.com; h=from:subject:message-id; bh=6Vq2LsRK/4jiYa/npkCuXmW6QF4BbW5GSecwBZSxdcI=; b=U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgguRCc5X8/UX9M40lkMnr//aFGOhce x5ezt8MFNUFlqYAAAAGcGF0YXR0AAAAAAAAAAZzaGE1MTIAAABTAAAAC3NzaC1lZDI1NTE5AAAA QH6rfP/je5CBrV2Jby9mnvCs0cF3g4KzP79mNzoDtuBgIKQoDkGjqs0qNmfdqL272G6H56/P0nd IxpFrS7ofxgo= X-Developer-Key: i=rbm@suse.com; a=openssh; fpr=SHA256:pzhe0fJpYLz+3cZ33FFPhIfaUElk9CXPFFXmalIH+1g When booting with the 'ipv6.disable=3D1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. If bonding ARP/NS validation is enabled, an IPv6 NS/NA packet received on a slave can reach bond_validate_na(), which calls bond_has_this_ip6(). That path calls ipv6_chk_addr() and can crash in __ipv6_chk_addr_and_flags(). BUG: kernel NULL pointer dereference, address: 00000000000005d8 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:__ipv6_chk_addr_and_flags+0x69/0x170 Call Trace: ipv6_chk_addr+0x1f/0x30 bond_validate_na+0x12e/0x1d0 [bonding] ? __pfx_bond_handle_frame+0x10/0x10 [bonding] bond_rcv_validate+0x1a0/0x450 [bonding] bond_handle_frame+0x5e/0x290 [bonding] ? srso_alias_return_thunk+0x5/0xfbef5 __netif_receive_skb_core.constprop.0+0x3e8/0xe50 ? srso_alias_return_thunk+0x5/0xfbef5 ? update_cfs_rq_load_avg+0x1a/0x240 ? srso_alias_return_thunk+0x5/0xfbef5 ? __enqueue_entity+0x5e/0x240 __netif_receive_skb_one_core+0x39/0xa0 process_backlog+0x9c/0x150 __napi_poll+0x30/0x200 ? srso_alias_return_thunk+0x5/0xfbef5 net_rx_action+0x338/0x3b0 handle_softirqs+0xc9/0x2a0 do_softirq+0x42/0x60 __local_bh_enable_ip+0x62/0x70 __dev_queue_xmit+0x2d3/0x1000 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? packet_parse_headers+0x10a/0x1a0 packet_sendmsg+0x10da/0x1700 ? kick_pool+0x5f/0x140 ? srso_alias_return_thunk+0x5/0xfbef5 ? __queue_work+0x12d/0x4f0 __sys_sendto+0x1f3/0x220 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x101/0xf80 ? exc_page_fault+0x6e/0x170 ? srso_alias_return_thunk+0x5/0xfbef5 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by adding an early check in bond_confirm_addr6(). If ipv6_stub->nd_tbl is NULL, return before calling ipv6_chk_addr(). Suggested-by: Fernando Fernandez Mancera Fixes: 4e24be018eb9 ("bonding: add new parameter ns_targets") Signed-off-by: Ricardo B. Marli=C3=A8re --- drivers/net/bonding/bond_main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_mai= n.c index a1de08ee3815..013d037b644a 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -90,6 +90,7 @@ #include #endif #include +#include #include #include =20 @@ -3251,6 +3252,9 @@ static int bond_confirm_addr6(struct net_device *dev, { struct in6_addr *addr =3D (struct in6_addr *)priv->data; =20 + if (!ipv6_stub->nd_tbl) + return 0; + return ipv6_chk_addr(dev_net(dev), addr, dev, 0); } =20 --=20 2.53.0