From nobody Mon Apr 13 21:02:55 2026 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 90C093033E9; Wed, 4 Mar 2026 08:20:24 +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=1772612424; cv=none; b=rEAFYo/lN4HC8YWax4wd8t2aEIp5GGagadjCogQpqPhDhd1uBvmUoqcyhcpheyCK3ay5Etbes/ZSxzD3sprQXQYF5DLjbAs48KUHzUUiI9cYWzNrm6nob7SZ4VieZYen1rksm6mhNUmCXGoLX2LKqOLCqtn7rGwx55OLb9iCIlA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772612424; c=relaxed/simple; bh=LgsT2ZLIn1tM6EIVIbCNe9NLt6lkZlMPPb9/TSVpbPY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=jeKHu1QD7CWurP22Poji4p2f6c8Fju8AKpuJRdpSS1EL9eHq7iF//rGfZTfpbNK89Ar3wUGkVxmoQJ3KOIyxRJYpT+SzAMM13BbQppQEk19AbFrWwKUWQcyVbzHLGSdq1OMV6j5J9Zcq7iIz6JcWggvMPgX4NVGwEae7WiKPujA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n5VC+SeO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="n5VC+SeO" Received: by smtp.kernel.org (Postfix) with ESMTPS id 10378C19425; Wed, 4 Mar 2026 08:20:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772612424; bh=LgsT2ZLIn1tM6EIVIbCNe9NLt6lkZlMPPb9/TSVpbPY=; h=From:Date:Subject:To:Cc:Reply-To:From; b=n5VC+SeOLL+FOp9tniAIyKI9vsveNDh5ND0y7WUsMQWPMDNsaKY+EuSQFmrRlF2mr DXHe/d8XYzzI17jixvJy0YPlSgJginzKT55X0bRwH8JPYKNmxo3Np7nKv7Op28qyRe RkHned9OW2S48hYrafWsDQ+Avj/zZSH+zUidBmkaXf1Ja3zFHo1u1MyO5yqATmLi4U XxcRBrEXXzWou1EA1CF2CYW/uJI1txHpL3AwaVyDmDqCVvu0746DVeWacrHX0iKS3r ZtgJLm321Bki3uIYRx9OSisbyHTmC4WKYGSrke96KZyR7x9bLq/j/lN6kioAL4Q65U VtVXRJ806sa7A== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0117EB7EA4; Wed, 4 Mar 2026 08:20:23 +0000 (UTC) From: Maximilian Pezzullo via B4 Relay Date: Wed, 04 Mar 2026 09:20:23 +0100 Subject: [PATCH] net: bridge: fix NULL dereference in br_do_suppress_nd when ipv6.disable=1 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: <20260304-br-nd-suppress-ipv6-null-fix-v1-1-084356ba8257@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/x2MQQqDMBAAvyJ77kISNQW/Ij1E3bQLIQ1ZFEHyd xePMwxzgVBlEpi6CyodLPzPCvbVwfoL+UvImzI447zpzYBLxbyh7KVUEkEuh8e8p4SRTzRhtD6 u7h1tAF1oo/rZz5/Wbl62a91uAAAA X-Change-ID: 20260304-br-nd-suppress-ipv6-null-fix-0a516fc27f1a To: Nikolay Aleksandrov , Ido Schimmel , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: bridge@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Guruprasad C P , Maximilian Pezzullo X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1772612423; l=1381; i=maximilianpezzullo@gmail.com; s=20260303; h=from:subject:message-id; bh=HvIRU/i10xnVMJH/+ZNsf/sb22J8jejklG20d/MkhlI=; b=H1UIZ23bHg2tUhPT/B36gsRLVgF6dOQrgedgYPa2gB8N3k2aMndRbMNRp4MyC68a1YB916q2k IM7hHazRSNcBZO/shE3Z1glFxiwlDELetWeaLorRqMzb6U+TS9nqXKb X-Developer-Key: i=maximilianpezzullo@gmail.com; a=ed25519; pk=TRTR4c2Vb1IfluQvv5OUDPg7EE+pIzdPBND85UU559w= X-Endpoint-Received: by B4 Relay for maximilianpezzullo@gmail.com/20260303 with auth_id=658 X-Original-From: Maximilian Pezzullo Reply-To: maximilianpezzullo@gmail.com From: Maximilian Pezzullo When the kernel is booted with ipv6.disable=3D1, the IPv6 module loads but skips full initialization, leaving ipv6_stub as NULL. If the bridge neigh_suppress feature is enabled on a port and an ICMPv6 Neighbor Solicitation arrives, br_do_suppress_nd() calls neigh_lookup() via ipv6_stub->nd_tbl without first checking whether ipv6_stub is valid, causing a kernel panic. Fix this by returning early if ipv6_stub or its nd_tbl pointer is NULL. Reported-by: Guruprasad C P Closes: https://bugzilla.kernel.org/show_bug.cgi?id=3D221143 Signed-off-by: Maximilian Pezzullo --- net/bridge/br_arp_nd_proxy.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/bridge/br_arp_nd_proxy.c b/net/bridge/br_arp_nd_proxy.c index 1e2b51769eec..0b1b9ba29b7d 100644 --- a/net/bridge/br_arp_nd_proxy.c +++ b/net/bridge/br_arp_nd_proxy.c @@ -455,6 +455,9 @@ void br_do_suppress_nd(struct sk_buff *skb, struct net_= bridge *br, return; } =20 + if (!ipv6_stub || !ipv6_stub->nd_tbl) + return; + n =3D neigh_lookup(ipv6_stub->nd_tbl, &msg->target, vlandev); if (n) { struct net_bridge_fdb_entry *f; --- base-commit: af4e9ef3d78420feb8fe58cd9a1ab80c501b3c08 change-id: 20260304-br-nd-suppress-ipv6-null-fix-0a516fc27f1a Best regards, --=20 Maximilian Pezzullo