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 7D06C3396EE; Mon, 20 Apr 2026 15:51:24 +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=1776700284; cv=none; b=L5lva7wQ6NQKDlCWEjpaunqB/o7ODMPxJrxz9gddq/sT3yxBziRxLN7/2HZIrWMyCX2tUXOgVFvDzBFK5bEAIUOxPXGlGyvoCYEOgYWBjeMkWJJ9ymg/05Z8hD4VGZjbPHbjTZ0/UPxV+0L0CXjaWKruY1ChhUdaPlR7vvW/iuA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776700284; c=relaxed/simple; bh=OvP3SmeFi7+CJyHTfOPZlPd3wFxzAWGs/wq8cJheV5I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Cpk2dRXAh/4gD08C48NSd2XP/aYaYmFmjGqxAF9AJxxV+UNAdj6UiZhW487uEOaS6fxzsCIcPldplujyJUayWmzpoqMO6xK0WNKTf3Ty5OfrdDdVhbsv/P+XcExKAMFdT+XI4rtootPZs1I0goHWoO7YM8BTCNUk8tebWIrbE1Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uiFfgVM+; 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="uiFfgVM+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1446DC19425; Mon, 20 Apr 2026 15:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776700284; bh=OvP3SmeFi7+CJyHTfOPZlPd3wFxzAWGs/wq8cJheV5I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uiFfgVM+Ue3PUCF+iQxRxn/lp0eO11rOmbQ95Qb7BDHo6KXBsMI1hy2MmlAXPkINp iy/v/wInnV+UNf+AGRcs06PIhfDi8IJ7hrjtrZ5EkDVGWzWAzy9ugAN0qkrS0JVsan fiD8u22SwMBumtzYIB7Zt+3YjV8lfxv7bV0Cb/wU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Maciej Fijalkowski , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.19 105/220] xsk: validate MTU against usable frame size on bind Date: Mon, 20 Apr 2026 17:40:46 +0200 Message-ID: <20260420153937.815205042@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153934.013228280@linuxfoundation.org> References: <20260420153934.013228280@linuxfoundation.org> User-Agent: quilt/0.69 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Maciej Fijalkowski [ Upstream commit 36ee60b569ba0dfb6f961333b90d19ab5b323fa9 ] AF_XDP bind currently accepts zero-copy pool configurations without verifying that the device MTU fits into the usable frame space provided by the UMEM chunk. This becomes a problem since we started to respect tailroom which is subtracted from chunk_size (among with headroom). 2k chunk size might not provide enough space for standard 1500 MTU, so let us catch such settings at bind time. Furthermore, validate whether underlying HW will be able to satisfy configured MTU wrt XSK's frame size multiplied by supported Rx buffer chain length (that is exposed via net_device::xdp_zc_max_segs). Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-5-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/xdp/xsk_buff_pool.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c index 6799ab6672f3e..1f96bdf1e7a60 100644 --- a/net/xdp/xsk_buff_pool.c +++ b/net/xdp/xsk_buff_pool.c @@ -10,6 +10,8 @@ #include "xdp_umem.h" #include "xsk.h" +#define ETH_PAD_LEN (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN) + void xp_add_xsk(struct xsk_buff_pool *pool, struct xdp_sock *xs) { if (!xs->tx) @@ -158,8 +160,12 @@ static void xp_disable_drv_zc(struct xsk_buff_pool *pool) int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, u16 queue_id, u16 flags) { + u32 needed = netdev->mtu + ETH_PAD_LEN; + u32 segs = netdev->xdp_zc_max_segs; + bool mbuf = flags & XDP_USE_SG; bool force_zc, force_copy; struct netdev_bpf bpf; + u32 frame_size; int err = 0; ASSERT_RTNL(); @@ -179,7 +185,7 @@ int xp_assign_dev(struct xsk_buff_pool *pool, if (err) return err; - if (flags & XDP_USE_SG) + if (mbuf) pool->umem->flags |= XDP_UMEM_SG_FLAG; if (flags & XDP_USE_NEED_WAKEUP) @@ -201,8 +207,24 @@ int xp_assign_dev(struct xsk_buff_pool *pool, goto err_unreg_pool; } - if (netdev->xdp_zc_max_segs == 1 && (flags & XDP_USE_SG)) { - err = -EOPNOTSUPP; + if (mbuf) { + if (segs == 1) { + err = -EOPNOTSUPP; + goto err_unreg_pool; + } + } else { + segs = 1; + } + + /* open-code xsk_pool_get_rx_frame_size() as pool->dev is not + * set yet at this point; we are before getting down to driver + */ + frame_size = __xsk_pool_get_rx_frame_size(pool) - + xsk_pool_get_tailroom(mbuf); + frame_size = ALIGN_DOWN(frame_size, 128); + + if (needed > frame_size * segs) { + err = -EINVAL; goto err_unreg_pool; } -- 2.53.0