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 B96053DDAF4 for ; Fri, 21 Aug 2026 14:49:43 +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=1787323785; cv=none; b=VtiQLYlrB8TlEhBVz0MVQVZJfADcfwkt+WjquOVuIYUgLLcqucCqNDKGpaTjHvg+8kb4nn88tNYQu1H74WD0sfmOfrSkvIR0pbuR21B4cn9JAkVlUgMYbWgRp9oWzyzhGqx5Z2ScE+Gbui8drYNqSoBDNbBj52APNjw6sZo7zt4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787323785; c=relaxed/simple; bh=nkwKh07Oy6sZnXe+LTAxrtL2dfiW1sBTE159eHjkFCQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TopEfrJ7lJzJ4flA09AKt3T3kVidAk8SXxqYeoDtos7YCjMeTW/hI9AkcCGXUXd6IshNjqamWdjHLEkMwa1yUeJ7JxxIeA3SJu0On4DUWAUqvyn7ptmx2zuCWTQD3L+TyEO7Y0QHroO+BhlRrUFDHCftd207DFhp6566xeucRX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bs6uV4n5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bs6uV4n5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A27F1F00A3A; Fri, 21 Aug 2026 14:49:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787323783; bh=uP1CAYLz0XB5GzQcHHM5X0OjdyWARjTxijjtHl405qs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Bs6uV4n54fB2HmWeplT8MDfxqAQSTcf8yI/IWLPES9YlngkLyjZCrMDA9ZnrvrYv/ r1PR6k7KEb7QSaOhJ4MbQeQtXurH8xZuCBJRnMowWAwvQZKIuHlFdv44csXJUFIT8g exo4u9muUO0P1jGNcJdJrzqac5dpYt/Xoe+zcJLFM62ebnGF6YGAMBztwm4tud/K/T 6KVXPCZ16VMevC1TQL4G7d6UbXR9pbiV55VRTLZ3P56o7Hizw9lmZoqrgdP3olTlWd NuSDAy6knKU7Aa48SjguppeLHor/Z7MD7QOYBgaeOGPCeSjSocPg43IDEW5j2J9fY4 ou6zCkybU0XBA== From: Sasha Levin To: stable@vger.kernel.org Cc: Zihan Xi , Vega , Paolo Abeni , Sasha Levin Subject: [PATCH 6.1.y 2/2] packet: synchronize pressure clearing with ring reconfiguration Date: Fri, 21 Aug 2026 10:49:40 -0400 Message-ID: <20260821144940.3429010-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260821144940.3429010-1-sashal@kernel.org> References: <2026081734-marrow-captive-bde1@gregkh> <20260821144940.3429010-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zihan Xi [ Upstream commit 1a35da325cac4d5bcad76a2aa943408a6f1d9000 ] packet_set_ring() updates the RX ring state under sk_receive_queue.lock, but used to publish the tpacket receive mode through po->prot_hook.func after releasing that lock. packet_poll() and packet_recvmsg() can then run the pressure clearing path after the ring has been cleared while still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference stale or NULL ring storage. Move the existing receive hook assignment into the same sk_receive_queue.lock section as the ring state update. Keep the assignment otherwise unchanged, including on TX ring reconfiguration, to avoid adding behavior changes that are not required for the fix. Serialize packet_recvmsg() pressure clearing with the same queue lock only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear and the socket has moved away from tpacket_rcv, packet_set_ring() has already detached the socket and waited for synchronize_net(), so no new packet input can set the flag again. packet_poll() already holds sk_receive_queue.lock, so it uses the new unlocked helper directly. Fixes: 2ccdbaa6d55b ("packet: rollover lock contention avoidance") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: Codex:gpt-5.4 Signed-off-by: Zihan Xi Link: https://patch.msgid.link/f90b5688311fa278d1361ea8c6be0bf25967d591.1785247446.git.zihanx@nebusec.ai Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/packet/af_packet.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 0738fef357350..55b9af053e026 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1370,13 +1370,25 @@ static int packet_rcv_has_room(struct packet_sock *po, struct sk_buff *skb) return ret; } -static void packet_rcv_try_clear_pressure(struct packet_sock *po) +static void __packet_rcv_try_clear_pressure(struct packet_sock *po) { if (packet_sock_flag(po, PACKET_SOCK_PRESSURE) && __packet_rcv_has_room(po, NULL) == ROOM_NORMAL) packet_sock_flag_set(po, PACKET_SOCK_PRESSURE, false); } +static void packet_rcv_try_clear_pressure(struct packet_sock *po) +{ + struct sock *sk = &po->sk; + + if (!packet_sock_flag(po, PACKET_SOCK_PRESSURE)) + return; + + spin_lock_bh(&sk->sk_receive_queue.lock); + __packet_rcv_try_clear_pressure(po); + spin_unlock_bh(&sk->sk_receive_queue.lock); +} + static void packet_sock_destruct(struct sock *sk) { skb_queue_purge(&sk->sk_error_queue); @@ -4330,7 +4342,7 @@ static __poll_t packet_poll(struct file *file, struct socket *sock, TP_STATUS_KERNEL)) mask |= EPOLLIN | EPOLLRDNORM; } - packet_rcv_try_clear_pressure(po); + __packet_rcv_try_clear_pressure(po); spin_unlock_bh(&sk->sk_receive_queue.lock); spin_lock_bh(&sk->sk_write_queue.lock); if (po->tx_ring.pg_vec) { @@ -4570,14 +4582,14 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, rb->frame_max = (req->tp_frame_nr - 1); rb->head = 0; rb->frame_size = req->tp_frame_size; + po->prot_hook.func = (po->rx_ring.pg_vec) ? + tpacket_rcv : packet_rcv; spin_unlock_bh(&rb_queue->lock); swap(rb->pg_vec_order, order); swap(rb->pg_vec_len, req->tp_block_nr); rb->pg_vec_pages = req->tp_block_size/PAGE_SIZE; - po->prot_hook.func = (po->rx_ring.pg_vec) ? - tpacket_rcv : packet_rcv; skb_queue_purge(rb_queue); if (atomic_long_read(&po->mapped)) pr_err("packet_mmap: vma is busy: %ld\n", -- 2.53.0