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 8103B3491D5; Tue, 21 Oct 2025 16:25:16 +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=1761063916; cv=none; b=BlljcJy7QH0oBWf8rz+RqKRfOI2dMhcV/e6bjhDO0+E7LCewTOxpgvSZwhoaiUQw0ItDuCm6i3ii/Awn9vEX9rz6c/DLpHalAMI5ggtPgw+J4QH9Mad4ABTwD7QLHoPRk1sY+YZIG+9p0Dm4g97cEfLsB6U/YZkVI+pn2GXRJro= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761063916; c=relaxed/simple; bh=q0fhm0UR6QPcn3oQ7i939P5mKJ7p0W/EmSLFSGX90zY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cYAJ07N0vYWw8BbYc5zsY4pESfCNUyQLdVSPsI5VP5Gnhqx6Pn240lnFZsmehLzWWGStQcSku+yn73ZRG0bFuAPg0PVczaTNe6skgTd2coE3ahukP9Y3hhupE7ikhaqSe+esqI6d0x2dqH0cmarPTZX7pQiQdCxw1v64av5OJws= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IQ2+uzR8; 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="IQ2+uzR8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D857C4CEF1; Tue, 21 Oct 2025 16:25:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761063916; bh=q0fhm0UR6QPcn3oQ7i939P5mKJ7p0W/EmSLFSGX90zY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IQ2+uzR8mOu5SxDT16hElWK+RiqF3yuyLHZv/xfK/ipAsd2qBEoP6JOjbfVvowHuy lvovRXCN1Kvszu51kiaycpQzrVamdTCBu3zUDT43YRJPG0tcg4Q+Z7SRG8mu0LbFCd xwc5K98e8BRKvcwt7P8AUSa4oM6LQrxo+bQFqb1KwgQDvBBK/ceRFWve1PPNBZvjpN vUlx0DGWRMVwrIhk4IwmCCMyJOM39/pu/HruIE6V0xWsC+7rBCzCZaMDckfHHTIPHJ E8+ZxkOrRYFyKPJkjEh+1O1jTX48WjnyH+ceMNmf8suBJMOTZNrL2oxxhUwz+KpLGB Ev7x2dM7vueRw== Date: Tue, 21 Oct 2025 17:25:12 +0100 From: Simon Horman To: Fernando Fernandez Mancera Cc: netdev@vger.kernel.org, csmate@nop.hu, kerneljasonxing@gmail.com, maciej.fijalkowski@intel.com, bjorn@kernel.org, sdf@fomichev.me, jonathan.lemon@gmail.com, bpf@vger.kernel.org Subject: Re: [PATCH net] xsk: avoid data corruption on cq descriptor number Message-ID: References: <20251021150656.6704-1-fmancera@suse.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251021150656.6704-1-fmancera@suse.de> On Tue, Oct 21, 2025 at 05:06:56PM +0200, Fernando Fernandez Mancera wrote: ... > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c ... > @@ -774,6 +777,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > { > struct net_device *dev = xs->dev; > struct sk_buff *skb = xs->skb; > + struct page *page; > int err; > > if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) { > @@ -791,6 +795,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > len = desc->len; > > if (!skb) { > + struct xsk_addr_node *head_addr; > + > hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom)); > tr = dev->needed_tailroom; > skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); > @@ -804,7 +810,13 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > if (unlikely(err)) > goto free_err; > > - xsk_skb_init_misc(skb, xs, desc->addr); > + head_addr = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL); > + if (!head_addr) { > + __free_page(page); Hi Fernando, Perhaps the page changes to xsk_build_skb() aren't needed because page seems to be uninitialised here. Flagged by W=1 builds with Clang 21.1.1, and Smatch. > + err = -ENOMEM; > + goto free_err; > + } > + xsk_skb_init_misc(skb, xs, head_addr, desc->addr); > if (desc->options & XDP_TX_METADATA) { > err = xsk_skb_metadata(skb, buffer, desc, > xs->pool, hr); > @@ -814,7 +826,6 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > } else { > int nr_frags = skb_shinfo(skb)->nr_frags; > struct xsk_addr_node *xsk_addr; > - struct page *page; > u8 *vaddr; > > if (unlikely(nr_frags == (MAX_SKB_FRAGS - 1) && xp_mb_desc(desc))) { > @@ -843,7 +854,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, > refcount_add(PAGE_SIZE, &xs->sk.sk_wmem_alloc); > > xsk_addr->addr = desc->addr; > - list_add_tail(&xsk_addr->addr_node, &XSKCB(skb)->addrs_list); > + list_add_tail(&xsk_addr->addr_node, &XSK_TX_HEAD(skb)->addr_node); > } > } > > -- > 2.51.0 > >