From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C09C4315A; Sun, 7 Sep 2025 20:42:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757277774; cv=none; b=HC4CBoxV4XmRb8gtS/6+6ILQjbcDQzQcvqB18xHm6gUeZ6kvl9JLKJDHIyyWk0DenCx1G55qSKjBxBGIMbbnfRKnPXAcN0HoTarpk7oLdgWnzmbl34AbVkFn1qCnDZsaCwJM7Zn2HXPaKjAI15yPekGS0bq4Qe+iOlI6gRDdrNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757277774; c=relaxed/simple; bh=797g8PbeOLe2dbSN0g7TB9FQqdkDPY9MMMjPBy5nX+U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HxS3zi8a0R3UVjaJpjWdnpzssPCOo1S9WAGP4lfCZOPmiIPIfMCqlEFr4pyrfuJYYH79obRmlBCZER1BWFicUE9/YZJJ9bs8grXfde3oYUQ2cUujwXk9tcdpOEVJz+AsR2Fsh4XZoUJz/F7PbvYl/jAIgp/OOpA88AuPg8TFjTE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RgDiXFOo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RgDiXFOo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00F2FC4CEF0; Sun, 7 Sep 2025 20:42:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1757277774; bh=797g8PbeOLe2dbSN0g7TB9FQqdkDPY9MMMjPBy5nX+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RgDiXFOoyNQKFvKCvVWB8mZINheVAAiwFX/3m2yftCL2pnYejVJvzfxAgyVuxwTBy JrwKrSJehONgzKRcSrnfqwcLKOCnGL2xxGSSXqrrcKEOjfsNgcTJz7UoLrh+ooaxHX vJ6Ds3ixdZBJykZBsV6XsCpfa9tZt70/GRynM5Ss= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Petr Machata , Ido Schimmel , Nikolay Aleksandrov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.16 076/183] vxlan: Fix NPD in {arp,neigh}_reduce() when using nexthop objects Date: Sun, 7 Sep 2025 21:58:23 +0200 Message-ID: <20250907195617.603390904@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250907195615.802693401@linuxfoundation.org> References: <20250907195615.802693401@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ido Schimmel [ Upstream commit 1f5d2fd1ca04a23c18b1bde9a43ce2fa2ffa1bce ] When the "proxy" option is enabled on a VXLAN device, the device will suppress ARP requests and IPv6 Neighbor Solicitation messages if it is able to reply on behalf of the remote host. That is, if a matching and valid neighbor entry is configured on the VXLAN device whose MAC address is not behind the "any" remote (0.0.0.0 / ::). The code currently assumes that the FDB entry for the neighbor's MAC address points to a valid remote destination, but this is incorrect if the entry is associated with an FDB nexthop group. This can result in a NPD [1][3] which can be reproduced using [2][4]. Fix by checking that the remote destination exists before dereferencing it. [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 4 UID: 0 PID: 365 Comm: arping Not tainted 6.17.0-rc2-virtme-g2a89cb21162c #2 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:vxlan_xmit+0xb58/0x15f0 [...] Call Trace: dev_hard_start_xmit+0x5d/0x1c0 __dev_queue_xmit+0x246/0xfd0 packet_sendmsg+0x113a/0x1850 __sock_sendmsg+0x38/0x70 __sys_sendto+0x126/0x180 __x64_sys_sendto+0x24/0x30 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [2] #!/bin/bash ip address add 192.0.2.1/32 dev lo ip nexthop add id 1 via 192.0.2.2 fdb ip nexthop add id 10 group 1 fdb ip link add name vx0 up type vxlan id 10010 local 192.0.2.1 dstport 4789 proxy ip neigh add 192.0.2.3 lladdr 00:11:22:33:44:55 nud perm dev vx0 bridge fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10 arping -b -c 1 -s 192.0.2.1 -I vx0 192.0.2.3 [3] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 13 UID: 0 PID: 372 Comm: ndisc6 Not tainted 6.17.0-rc2-virtmne-g6ee90cb26014 #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1v996), BIOS 1.17.0-4.fc41 04/01/2x014 RIP: 0010:vxlan_xmit+0x803/0x1600 [...] Call Trace: dev_hard_start_xmit+0x5d/0x1c0 __dev_queue_xmit+0x246/0xfd0 ip6_finish_output2+0x210/0x6c0 ip6_finish_output+0x1af/0x2b0 ip6_mr_output+0x92/0x3e0 ip6_send_skb+0x30/0x90 rawv6_sendmsg+0xe6e/0x12e0 __sock_sendmsg+0x38/0x70 __sys_sendto+0x126/0x180 __x64_sys_sendto+0x24/0x30 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f383422ec77 [4] #!/bin/bash ip address add 2001:db8:1::1/128 dev lo ip nexthop add id 1 via 2001:db8:1::1 fdb ip nexthop add id 10 group 1 fdb ip link add name vx0 up type vxlan id 10010 local 2001:db8:1::1 dstport 4789 proxy ip neigh add 2001:db8:1::3 lladdr 00:11:22:33:44:55 nud perm dev vx0 bridge fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10 ndisc6 -r 1 -s 2001:db8:1::1 -w 1 2001:db8:1::3 vx0 Fixes: 1274e1cc4226 ("vxlan: ecmp support for mac fdb entries") Reviewed-by: Petr Machata Signed-off-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20250901065035.159644-3-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/vxlan/vxlan_core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index cea9dd067b68a..45cec14d76f62 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -1880,6 +1880,7 @@ static int arp_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) n = neigh_lookup(&arp_tbl, &tip, dev); if (n) { + struct vxlan_rdst *rdst = NULL; struct vxlan_fdb *f; struct sk_buff *reply; @@ -1890,7 +1891,9 @@ static int arp_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) rcu_read_lock(); f = vxlan_find_mac_tx(vxlan, n->ha, vni); - if (f && vxlan_addr_any(&(first_remote_rcu(f)->remote_ip))) { + if (f) + rdst = first_remote_rcu(f); + if (rdst && vxlan_addr_any(&rdst->remote_ip)) { /* bridge-local neighbor */ neigh_release(n); rcu_read_unlock(); @@ -2047,6 +2050,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) n = neigh_lookup(ipv6_stub->nd_tbl, &msg->target, dev); if (n) { + struct vxlan_rdst *rdst = NULL; struct vxlan_fdb *f; struct sk_buff *reply; @@ -2056,7 +2060,9 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) } f = vxlan_find_mac_tx(vxlan, n->ha, vni); - if (f && vxlan_addr_any(&(first_remote_rcu(f)->remote_ip))) { + if (f) + rdst = first_remote_rcu(f); + if (rdst && vxlan_addr_any(&rdst->remote_ip)) { /* bridge-local neighbor */ neigh_release(n); goto out; -- 2.50.1