From mboxrd@z Thu Jan 1 00:00:00 1970 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 0624E565116; Wed, 30 Sep 2026 17:47:38 +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=1790790459; cv=none; b=T7cWVNkrJR/O8Y3Gr62QSF1mb06zIIHRD2JRv1KZXLRZHXn7TCD1VsbH0H8u+TYdfVy7AQ2GQt/0uydmmufCDqW33n1lAowpqdGK7/V5Kr7xT18RYQ6uz0ULWtVVEw4juocaiT23o7bQ+O82XHqOSlZE7HmyUeHtHtAU2g4exuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790790459; c=relaxed/simple; bh=47CvjR4N8BR3cMKxNJN8whzVpTNelNRvLLl6QUz5L6M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XbAJVI7BU3KejI94g4SyZq2tJR7UlY3MmexQdij70rZifgsUYyPXjZKN8EymgHsIK2eq0MctBEf5hlsHdMZfIjp236qm3h2SmZQfadx+xzUnKJ6hrI45ersth8mSu6Wcs/ywmAnp/3+J/0lJMsQZdqllpa/MZRvSRtd4TF4Ub94= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GR+dsc3X; 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="GR+dsc3X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 601E51F000FF; Wed, 30 Sep 2026 17:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790790457; bh=TyX/rELUX3+WLb32i+iDPTLf2GgaZTrYcNGNfzHqHn8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GR+dsc3XEwNEWYAlTq7OPuCp1vFFN4eAI4fZPNGHOOY+cbd+Xity73WMrqJeaDl/B +Q/Tqsti4HtNuunhR6YGNW4ijARO6iJuHY7xM28Vjx2gqV3W7XTXM4TjqkPwyFHTrp u2+IR7CqB6//EQPmcsXTpXFgs9hFXHxOmm+mltME= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Katherine Leaver , Bjoern Doebel , Willem de Bruijn , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 837/877] packet: use ubuf_info completion for TX_RING packets Date: Wed, 30 Sep 2026 17:29:08 +0200 Message-ID: <20260930152432.798163789@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn [ Upstream commit 9518405613863d0bf0700927a21367f5942cf058 ] tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called. A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb. Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree. The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set. To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels. The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete. Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring. As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch. Revert the now unused previous skb_zcopy_.._nouarg infra. Depends on commit 992cc9f94ca9 ("net/packet: defer vmalloc TX_RING free until skbs finish"). Reported-by: Katherine Leaver Reported-by: Bjoern Doebel Closes: https://lore.kernel.org/netdev/20260909085542.3370986-1-doebel@amazon.de/ Fixes: 5cd8d46ea156 ("packet: copy user buffers before orphan or clone") Cc: stable@vger.kernel.org Signed-off-by: Willem de Bruijn Link: https://patch.msgid.link/20260919004748.1463985-3-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski [ Retained sockc->tsflags instead of sockc in skb_setup_tx_timestamp() for the older helper signature. ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 19 --------- net/packet/af_packet.c | 102 ++++++++++++++++++++++++++++++------------------- 2 files changed, 65 insertions(+), 56 deletions(-) --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1807,22 +1807,6 @@ static inline void skb_zcopy_set(struct } } -static inline void skb_zcopy_set_nouarg(struct sk_buff *skb, void *val) -{ - skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t) val | 0x1UL); - skb_shinfo(skb)->flags |= SKBFL_ZEROCOPY_FRAG; -} - -static inline bool skb_zcopy_is_nouarg(struct sk_buff *skb) -{ - return (uintptr_t) skb_shinfo(skb)->destructor_arg & 0x1UL; -} - -static inline void *skb_zcopy_get_nouarg(struct sk_buff *skb) -{ - return (void *)((uintptr_t) skb_shinfo(skb)->destructor_arg & ~0x1UL); -} - static inline void net_zcopy_put(struct ubuf_info *uarg) { if (uarg) @@ -1845,8 +1829,7 @@ static inline void skb_zcopy_clear(struc struct ubuf_info *uarg = skb_zcopy(skb); if (uarg) { - if (!skb_zcopy_is_nouarg(skb)) - uarg->ops->complete(skb, uarg, zerocopy_success); + uarg->ops->complete(skb, uarg, zerocopy_success); skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY; } --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2582,26 +2582,6 @@ drop_n_account: goto drop_n_restore; } -static void tpacket_destruct_skb(struct sk_buff *skb) -{ - struct packet_sock *po = pkt_sk(skb->sk); - - if (likely(po->tx_ring.pg_vec)) { - void *ph; - __u32 ts; - - ph = skb_zcopy_get_nouarg(skb); - - ts = __packet_set_timestamp(po, ph, skb); - __packet_set_status(po, ph, TP_STATUS_AVAILABLE | ts); - - packet_dec_pending(&po->tx_ring); - complete(&po->skb_completion); - } - - sock_wfree(skb); -} - static int __packet_snd_vnet_parse(struct virtio_net_hdr *vnet_hdr, size_t len) { if ((vnet_hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && @@ -2641,27 +2621,56 @@ static int packet_snd_vnet_parse(struct return 0; } +struct tpacket_uarg { + struct ubuf_info ubuf; + struct packet_sock *po; + void *ph; +}; + +static void tpacket_ubuf_complete(struct sk_buff *skb, struct ubuf_info *uarg, + bool success) +{ + struct tpacket_uarg *tu = container_of(uarg, struct tpacket_uarg, ubuf); + struct packet_sock *po = tu->po; + void *ph = tu->ph; + __u32 ts; + + DEBUG_NET_WARN_ON_ONCE(!skb); + + if (!refcount_dec_and_test(&uarg->refcnt)) + return; + + ts = __packet_set_timestamp(po, ph, skb); + __packet_set_status(po, ph, TP_STATUS_AVAILABLE | ts); + + packet_dec_pending(&po->tx_ring); + complete(&po->skb_completion); + + kfree(tu); + sk_free(&po->sk); +} + +static const struct ubuf_info_ops tpacket_ubuf_ops = { + .complete = tpacket_ubuf_complete, +}; + static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb, - void *frame, struct net_device *dev, void *data, int tp_len, + 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; int to_write, offset, len, nr_frags, len_max; struct socket *sock = po->sk.sk_socket; struct page *page; int err; - ph.raw = frame; - skb->protocol = proto; skb->dev = dev; skb->priority = READ_ONCE(po->sk.sk_priority); skb->mark = READ_ONCE(po->sk.sk_mark); skb_set_delivery_type_by_clockid(skb, sockc->transmit_time, po->sk.sk_clockid); skb_setup_tx_timestamp(skb, sockc->tsflags); - skb_zcopy_set_nouarg(skb, ph.raw); skb_reserve(skb, hlen); skb_reset_network_header(skb); @@ -2801,6 +2810,7 @@ static int tpacket_snd(struct packet_soc struct virtio_net_hdr vnet_hdr; bool has_vnet_hdr = false; struct sockcm_cookie sockc; + struct tpacket_uarg *uarg; __be16 proto; int err, reserve = 0; void *ph; @@ -2928,7 +2938,7 @@ static int tpacket_snd(struct packet_soc err = len_sum; goto out_status; } - tp_len = tpacket_fill_skb(po, skb, ph, dev, data, tp_len, proto, + tp_len = tpacket_fill_skb(po, skb, dev, data, tp_len, proto, addr, hlen, copylen, hard_header_len, &sockc); if (likely(tp_len >= 0) && @@ -2960,7 +2970,24 @@ tpacket_error: virtio_net_hdr_set_proto(skb, &vnet_hdr); } - skb->destructor = tpacket_destruct_skb; + uarg = kmalloc(sizeof(*uarg), GFP_KERNEL); + if (unlikely(!uarg)) { + if (likely(len_sum > 0)) + err = len_sum; + else + err = -ENOMEM; + goto out_status; + } + uarg->po = po; + uarg->ph = ph; + uarg->ubuf.ops = &tpacket_ubuf_ops; + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG; + refcount_set(&uarg->ubuf.refcnt, 1); + + /* Hold a sk_wmem_alloc reference until completion */ + refcount_inc(&po->sk.sk_wmem_alloc); + skb_zcopy_init(skb, &uarg->ubuf); + __packet_set_status(po, ph, TP_STATUS_SENDING); packet_inc_pending(&po->tx_ring); @@ -4529,21 +4556,20 @@ static struct pgv *alloc_pg_vec(struct t vec->len = block_nr; pg_vec = vec->pg_vec; + if (tx_ring) { + vec->deferred = kzalloc_obj(*vec->deferred, + GFP_KERNEL | __GFP_NOWARN); + if (!vec->deferred) + goto out_free_pgvec; + vec->deferred->vec = vec; + INIT_DELAYED_WORK(&vec->deferred->work, + packet_free_pg_vec_work); + } + for (i = 0; i < block_nr; i++) { pg_vec[i].buffer = alloc_one_pg_vec_page(order); if (unlikely(!pg_vec[i].buffer)) goto out_free_pgvec; - - if (tx_ring && !vec->deferred && - is_vmalloc_addr(pg_vec[i].buffer)) { - vec->deferred = kzalloc_obj(*vec->deferred, - GFP_KERNEL | __GFP_NOWARN); - if (!vec->deferred) - goto out_free_pgvec; - vec->deferred->vec = vec; - INIT_DELAYED_WORK(&vec->deferred->work, - packet_free_pg_vec_work); - } } out: