Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C3A3F155A5D; Mon, 17 Aug 2026 13:56:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975016; cv=none; b=JlKmxmWyaK4FJwUTG4FSMkyr0WBNOHrGcUva/DdAxc3lFlAFzgKXfEVzn3iCP5e+aOPurZLzw2zppEk+tLN+pS3Zv2b1IqdRBY4b6xj7bW1HInleUsmoPSSj0gl29ARybptADTaC3NKDGNctlL3a56ymzidFXLru1t2Pz5zasWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975016; c=relaxed/simple; bh=8uSyX6YYmRYTa0zau3JFPeQLaX5M6VTJLDb+brmiFq0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Bacn1v23wlw8gAE/TY34kqNPw3iMpbjNFPEOjiiVeOiW2d0QRv9iSC3ZMvaDpEB+B3uWAw3D2aN1Ka6vz6fpyJoV6h4y2QUjKipb7C5iZPHxj1bvpvy6VjKQzNfvEcYdX5062WQ0SOfJgyV8ycAx4/RCn26fGze41jmFN1qj6Sc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Opfd0lIt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Opfd0lIt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28F061F000E9; Mon, 17 Aug 2026 13:56:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975015; bh=i9TBexPLZGJQaQSOiPRCWZBh7elwwOX9GtFYAv0tfRE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Opfd0lIt3MVhVhqr3ExkSRCCFmrYBBcz9wpYwFIgOQqFJ6r+F429sh993+r9qaRXl +5b+9XYM/5wBzHwftbIccLH7am6Mr2/CryHIjsOa1lfJbhhN1hWX84TEDnfRjCTZW0 U+QtbNkbLoC9/1uRz70w6mNMS3UjiLfwqJhADNYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Qihang Tang , Willem de Bruijn , Jakub Kicinski Subject: [PATCH 6.18 133/250] packet: use consistent hard_header_len in TX_RING send path Date: Mon, 17 Aug 2026 15:31:34 +0200 Message-ID: <20260817132542.013155715@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.466235697@linuxfoundation.org> References: <20260817132536.466235697@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-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qihang Tang commit 21b5953e7494c16a42e6cd8cf110e18d13ae4a6b upstream. tpacket_snd() reads dev->hard_header_len independently for skb allocation and header construction in tpacket_fill_skb(). Concurrent netdevice reconfiguration can therefore make the reserved headroom smaller than the amount later pushed, or make copylen - hard_header_len negative. Snapshot hard_header_len once before processing ring frames and use it for the frame limit, headroom allocation, copy length, and skb construction. Pass the snapshot to tpacket_fill_skb(). The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here. Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap") Cc: stable@vger.kernel.org Signed-off-by: Qihang Tang Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260805125729.19220-4-q.h.hack.winter@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2573,6 +2573,7 @@ static int packet_snd_vnet_parse(struct static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb, void *frame, struct net_device *dev, void *data, int tp_len, __be16 proto, unsigned char *addr, int hlen, int copylen, + int hard_header_len, const struct sockcm_cookie *sockc) { union tpacket_uhdr ph; @@ -2604,8 +2605,8 @@ static int tpacket_fill_skb(struct packe } else if (copylen) { int hdrlen = min_t(int, copylen, tp_len); - skb_push(skb, dev->hard_header_len); - skb_put(skb, copylen - dev->hard_header_len); + skb_push(skb, hard_header_len); + skb_put(skb, copylen - hard_header_len); err = skb_store_bits(skb, 0, data, hdrlen); if (unlikely(err)) return err; @@ -2736,7 +2737,7 @@ static int tpacket_snd(struct packet_soc void *data; int len_sum = 0; int status = TP_STATUS_AVAILABLE; - int hlen, tlen, copylen = 0; + int hard_header_len, hlen, tlen, copylen = 0; long timeo; mutex_lock(&po->pg_vec_lock); @@ -2783,8 +2784,9 @@ static int tpacket_snd(struct packet_soc goto out_put; } + hard_header_len = READ_ONCE(dev->hard_header_len); if (po->sk.sk_socket->type == SOCK_RAW) - reserve = dev->hard_header_len; + reserve = hard_header_len; size_max = po->tx_ring.frame_size - (po->tp_hdrlen - sizeof(struct sockaddr_ll)); @@ -2821,7 +2823,7 @@ static int tpacket_snd(struct packet_soc goto tpacket_error; status = TP_STATUS_SEND_REQUEST; - hlen = LL_RESERVED_SPACE(dev); + hlen = LL_RESERVED_SPACE_EX(dev, hard_header_len); tlen = dev->needed_tailroom; if (vnet_hdr_sz) { data += vnet_hdr_sz; @@ -2839,10 +2841,10 @@ static int tpacket_snd(struct packet_soc vnet_hdr.hdr_len); has_vnet_hdr = true; } - copylen = max_t(int, copylen, dev->hard_header_len); + copylen = max_t(int, copylen, hard_header_len); skb = sock_alloc_send_skb(&po->sk, hlen + tlen + sizeof(struct sockaddr_ll) + - (copylen - dev->hard_header_len), + (copylen - hard_header_len), !need_wait, &err); if (unlikely(skb == NULL)) { @@ -2852,7 +2854,8 @@ static int tpacket_snd(struct packet_soc goto out_status; } tp_len = tpacket_fill_skb(po, skb, ph, dev, data, tp_len, proto, - addr, hlen, copylen, &sockc); + addr, hlen, copylen, hard_header_len, + &sockc); if (likely(tp_len >= 0) && tp_len > dev->mtu + reserve && !vnet_hdr_sz &&