From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f41.google.com (mail-wm1-f41.google.com [209.85.128.41]) (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 A83E6270EC1 for ; Sat, 7 Mar 2026 20:51:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772916679; cv=none; b=RHW6RTUGOEqGHhqEWYw2PhvYOaQg2TYlw53shSqQwUvEFBFsR28ACEhPHyFZF1fbDI2Ob9uNxjpUv1lL1SiYgfRMp0tc6ITEyOr/YqOgB/EiQinMGYCHJZZbE4xf+6RfIbp6ORYVw7Ir6sa2M3IYAvYOdAv3Bj9MnAE4T8eIZiw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772916679; c=relaxed/simple; bh=LfIxcEnbfF8UcBAlQpsEC60tpSn836JRskSf+FgYy7k=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=QUUoef4xSwGeb7685pqdo4cxJQtlyxSAgDYFYrRTD7xC15wWkTGUiueMt6DjCm5mvX9vqWWEBWDYE8ISMAWjT6DKrx8ak+M5JqL8i2NSL8rM5Vy8tlNmeuef3dyrv6mMWXrF7MMYCpQaVb0LnEESw2ecxhTRE8LVHoOAto9XYy0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=NyJaqgXI; arc=none smtp.client-ip=209.85.128.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="NyJaqgXI" Received: by mail-wm1-f41.google.com with SMTP id 5b1f17b1804b1-48534237460so2571175e9.3 for ; Sat, 07 Mar 2026 12:51:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1772916676; x=1773521476; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=+8YSb3tz18QqaSJGIXy5ZYeSWZygMaMUDj6N+n+MakU=; b=NyJaqgXIlqFmQfADBmL2KrY9It4WrL7J0rOKiK+s03mgGOTAK2bCRLgTuAe96ZtQFa 2b7xtY5kWcLPmVpZGDJBCtofd8xSMpNot3ne6FWrPRxKkvjiPqf6d3xUmduUlxbQ2pn/ 1W5R4SZs0+BjBOO+yLasxVfYLROMWaKgD3eF+Ct8iK2d2dh7uRjtgswMpgrwzWldsdhx 78Z6vsnGg0tlp9ztQOLzRsnYnWvw5q78gbXUXM64IKpXnWZNakuzGxlWNi0zSHsJ7Qz8 wXJJOKZKPq3NXKzFDCBqdgJah1Q1dJHwYuqnRUSS9MtWVtugq04oCmFvhL2x6p3LWlu3 c5QA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772916676; x=1773521476; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=+8YSb3tz18QqaSJGIXy5ZYeSWZygMaMUDj6N+n+MakU=; b=otjf8QhGomxF5IVulU6MVx0UaAOmCMZeQiLmiNoFFiYDTWMIlC+pdbrrk0WLZwWYoS uRYD05OTtD5nrYxrOw4/MJvm8Q/cT0/T/ghvWK65AOKzfiLFzkHGkTV85lY3OqbvVPTc O2wMTKULyEAQaJl6bIKfSDKxQ9UemdUT4TuepsiBdMpfvbzCbbW3a655xemyZc4s1ugm w1A6Gngmy5rL+cOyRSkky5PN/0zUVa6yrtd9W/GYj729GTYqUJ0EBcjjZKc5oHsYqs+E p/4oC/twGM4mKQoKUsQPOW8QkWQUsiMmQb0JbgpUXkyZHirm0KAPcBLc67Yn5JYgQNpA ixsw== X-Forwarded-Encrypted: i=1; AJvYcCW/LEbLKfKzcfTsVldHNii8UmUP1hsBnfd3oyL60isApbs0OjHUsnNBCNBv3fkaYh5p7D1g8XQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yx/KCYxKypSMi1012LcnJ1mxbvy84qa9Ea4pktAZD02N7oX+Fzr 4y3OrFiNjlAtXfeXUD4sqG75rkFNipDCxJw5GyiHHlYCxhMrwXWqUmxOgBoToO9RCKk= X-Gm-Gg: ATEYQzxMJAo4lWSNQPbwGhUCjIcUE7hgWgHsYMJ4atjLI4d8AdRLVn6LYutFi6tnyZ+ PGABffJDKItpesms4vIEl+m1CciD9gAfsB46slon1ZJNA1SBk0GwpfMppW8vo1IdlK4HpInBIzr eJYR1YBw0N+bRK8oP9pxHYcDElKCXFbRt5huOO5yXXl/mw6f2nXMxEI1But7hVIicurxRIw1J4m 84WNQ6tFYebydj7vV8k5JWWdqAIPWjkaS++o4S0wTbGp1fJdkNSnPHsLtd7MyT/XbiMlQQbrNMD 41lA/3VAkPqdhKcbW+qQjIIYOw5mOs3ILiYfVKLXlRDI0uGj8hmo2RNZDAO/op3OQyr3a3n+2sU VKYgHKf9dx47STOlDLVU5bbvaZ80VP3H6k8ObNSueZxIaEIm16Qf4CyDIcaOU17d7IxNOsmAxvR hr9a4hlGmGJg== X-Received: by 2002:a05:600c:3e15:b0:485:2f8b:55e9 with SMTP id 5b1f17b1804b1-4852f8b5ca8mr40634795e9.26.1772916676004; Sat, 07 Mar 2026 12:51:16 -0800 (PST) Received: from localhost ([189.99.238.164]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-56b09b20d3bsm5854727e0c.16.2026.03.07.12.51.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Mar 2026 12:51:15 -0800 (PST) From: =?utf-8?q?Ricardo_B=2E_Marli=C3=A8re?= Date: Sat, 07 Mar 2026 17:50:56 -0300 Subject: [PATCH net v4 4/4] bpf: bpf_out_neigh_v6: Fix nd_tbl NULL dereference when IPv6 is disabled Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20260307-net-nd_tbl_fixes-v4-4-e2677e85628c@suse.com> References: <20260307-net-nd_tbl_fixes-v4-0-e2677e85628c@suse.com> In-Reply-To: <20260307-net-nd_tbl_fixes-v4-0-e2677e85628c@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=1772916658; l=1991; i=rbm@suse.com; h=from:subject:message-id; bh=LfIxcEnbfF8UcBAlQpsEC60tpSn836JRskSf+FgYy7k=; b=U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgguRCc5X8/UX9M40lkMnr//aFGOhce x5ezt8MFNUFlqYAAAAGcGF0YXR0AAAAAAAAAAZzaGE1MTIAAABTAAAAC3NzaC1lZDI1NTE5AAAA QA78kdashxAZg6QDOFTFJ5DdZ4/gEYZMYataFMliZwhtsqkFf/nfobnSy0f0fdVlTgoSW3hutmQ V6JaQ4aFi8AE= X-Developer-Key: i=rbm@suse.com; a=openssh; fpr=SHA256:pzhe0fJpYLz+3cZ33FFPhIfaUElk9CXPFFXmalIH+1g 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. 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 is disabled, drop the packet before neighbor lookup. Suggested-by: Fernando Fernandez Mancera Fixes: ba452c9e996d ("bpf: Fix bpf_redirect_neigh helper api to support supplying nexthop") Signed-off-by: Ricardo B. Marlière --- net/core/filter.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index ff02dbe4c94f..3344fa0789f0 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2228,6 +2228,9 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb, return -ENOMEM; } + if (unlikely(!ipv6_mod_enabled())) + goto out_drop; + rcu_read_lock(); if (!nh) { dst = skb_dst(skb); -- 2.53.0