From nobody Mon Feb 9 04:45:27 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 4006C25FA0E; Thu, 5 Feb 2026 14:44:18 +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=1770302659; cv=none; b=flpafulFtI81NW7xGg+D6lO6rZkjS7HCrbJqVOKVP+lQRpH031eCpgJhZtqVP0RJXxHcqH/zhv+FnG8+TNCChnTP9rI/WFdf7dbFWnrbQVgZ627Ng8QHKli8l3W+hn2FPT1N5EjGdm2KLi6rVx4mAQzbplbb+ue/R5E4HQh9Gx4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770302659; c=relaxed/simple; bh=dhAn/pdXg7ugA9PdDtASFAJ9YgV7T7ENgMTkgMTYLjo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=VxMQ5H07nTO4OYYYsALyqESwa4+vMkc3OyN/5XXSGf7DVPuy1cqQygsUL5beVBOOn+N64fc6JW/H+5+060MMYcGk9lFyjbLvw0p2bvEcmXLovd3AMprnsYU8lWjwejXYBI+GkjBp0v2QeW8NNHMH6tw03lDE+1e5aKnH/iQIcDg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WhUvjxhO; 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="WhUvjxhO" Received: by smtp.kernel.org (Postfix) with ESMTPS id C44A3C4CEF7; Thu, 5 Feb 2026 14:44:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770302658; bh=dhAn/pdXg7ugA9PdDtASFAJ9YgV7T7ENgMTkgMTYLjo=; h=From:Date:Subject:To:Cc:Reply-To:From; b=WhUvjxhOjk8bQjRijvx3dnBgorv/WZ4B7CY/A40IK7fkucWo2BzzUi2E6eAdyQ97E CouQCRw/NSLylWxgddTASHhaJTLVpSGYcUhdWt9WmPK/kpINPL/QvEeY7hD5SdVK9d A3x/xIYXGCBoaSTQXUUlcRINo0q7EkdxTUEyGvBDivOgz2mVRDxR7aKnGKoP2k0ZK+ 48xo2PYHY08lPPHCQYRkhKvRBZ9QfUA7Wa8sChBotwSU0CksqbgyzqhJ11Fzkg5cJz DPDE6TRj3mycyRhL3DJLZi/AxfHlMd2NkZyUuchIb8XT0oDqslIJI4Q3dn7PMXjvbo 9TkhZBzmYM+wA== 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 B6D24EC1EBC; Thu, 5 Feb 2026 14:44:18 +0000 (UTC) From: Oliver Hartkopp via B4 Relay Date: Thu, 05 Feb 2026 15:44:05 +0100 Subject: [PATCH net-next] net: skb: allow up to 8 skb extension ids 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: <20260205-skb_ext-v1-1-9ba992ccee8b@hartkopp.net> X-B4-Tracking: v=1; b=H4sIALSshGkC/x3MQQqAIBBA0avErBNUUqqrRITZVENgoRKCePek5 YfHzxDQEwYYmwweXwp0uxqibcCexh3IaKsNkkvNJVcsXOuCKTLDO6uFtUOvEKp+PO6U/tMEDiN zVcFcyge7h5FIYwAAAA== X-Change-ID: 20260205-skb_ext-a04c61cc985e To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Florian Westphal , Oliver Hartkopp X-Mailer: b4 0.15-dev-47773 X-Developer-Signature: v=1; a=ed25519-sha256; t=1770302657; l=1409; i=socketcan@hartkopp.net; s=20260128; h=from:subject:message-id; bh=0xitE6f4X80qvcsu6zLeGOS3GWowolncxL3u1M9XXik=; b=n7mqLSz6Ke5GE/kkdWHvZq0icKMYfF8vtVChShC/3Pj1o2qwuQicxhqZuvlIEHc6u3fuBuSNX szWiAd6OiGZCS808ERBK4qSl0NwLUh3b2aeJxVmxmM8uWgyFUyGlpVr X-Developer-Key: i=socketcan@hartkopp.net; a=ed25519; pk=/gU/7/wBqak3kTsTeFbCCqUi9dnh+1i6ITEkfPj/BvU= X-Endpoint-Received: by B4 Relay for socketcan@hartkopp.net/20260128 with auth_id=620 X-Original-From: Oliver Hartkopp Reply-To: socketcan@hartkopp.net From: Oliver Hartkopp The skb extension ids range from 0 .. 7 to fit their bits as flags into a single byte. The ids are automatically enumnerated in enum skb_ext_id in skbuff.h, where SKB_EXT_NUM is defined as the last value. When having 8 skb extension ids (0 .. 7), SKB_EXT_NUM becomes 8 which is a valid value for SKB_EXT_NUM. This patch intentionally lacks a Fixes tag. Backporting is pointless as former kernels did not use the entire range of skb extension ids. Link: https://lore.kernel.org/netdev/aXoMqaA7b2CqJZNA@strlen.de/ Reviewed-by: Florian Westphal Signed-off-by: Oliver Hartkopp --- net/core/skbuff.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 648c20e19038..609851d70173 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5156,11 +5156,11 @@ static __always_inline unsigned int skb_ext_total_l= ength(void) return l; } =20 static void skb_extensions_init(void) { - BUILD_BUG_ON(SKB_EXT_NUM >=3D 8); + BUILD_BUG_ON(SKB_EXT_NUM > 8); #if !IS_ENABLED(CONFIG_KCOV_INSTRUMENT_ALL) BUILD_BUG_ON(skb_ext_total_length() > 255); #endif =20 skbuff_ext_cache =3D kmem_cache_create("skbuff_ext_cache", --- base-commit: 021718d2cc1a2df2f53b06968fa89280199371bd change-id: 20260205-skb_ext-a04c61cc985e Best regards, -- =20 Oliver Hartkopp