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 3E34630EF68 for ; Mon, 17 Aug 2026 11:31:11 +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=1786966273; cv=none; b=DDh4X7KOs1yYMiQHOCfwqp87usG5pXsJLT0gPn5SjDUqMPom7cuglVykqeJ0rWxFdXsJpZ9mKpe/Su4VEP7bFpPk/iaJMFGKvYQGQzPEKTpvZTncLrq+owkLEoPXyCqlBOxFAQykgMaTf8iiNCzp4pWcdNJcrR0VKTrNJJRe9ig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786966273; c=relaxed/simple; bh=SUEzoRPHSra9+DSpgTKakQW3OnvEwu2R+jUOeatXEiI=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=N8EznoJl/KmAVr2WbKP5DEdqEHGgN9Y2iYOqXk0lGhigclxOSjRCGWHh+AyM8wxew3Sgr7OM1F4xGxtt3dyV2wPT+QhQfZhP0urZCvkWYnPj1GMqD7WYKpYk1bM/LRVDAQFxK6cFRrd55HNNHwq8dvOGuSzVadq0iQeaEuoVG+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=R/D9I5s+; 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="R/D9I5s+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A7191F000E9; Mon, 17 Aug 2026 11:31:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786966271; bh=rzOsRG8JGZ62FqkdBdGRIWXPd9IG5Os8nRo1qZNt+KA=; h=Subject:To:Cc:From:Date; b=R/D9I5s+LeQPLZL1C4i1b5kZ5Z+9jNO6LH9hLd/HeKRPXeiTMctUc97e4CfwnsWcV jd4Dax8oZ3DzgRsZKOiBl6ZYV2243lEQpDIeI8SBlCGd1UzbXV1P/zuZldNwAi5kS8 u6Z3E5AsQZp0IfffVEyIk5DGkBTN55hCHm4zL1BI= Subject: FAILED: patch "[PATCH] packet: synchronize pressure clearing with ring" failed to apply to 6.1-stable tree To: zihanx@nebusec.ai,pabeni@redhat.com,vega@nebusec.ai Cc: From: Date: Mon, 17 Aug 2026 13:29:34 +0200 Message-ID: <2026081734-marrow-captive-bde1@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 1a35da325cac4d5bcad76a2aa943408a6f1d9000 # git commit -s git send-email --to '' --in-reply-to '2026081734-marrow-captive-bde1@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1a35da325cac4d5bcad76a2aa943408a6f1d9000 Mon Sep 17 00:00:00 2001 From: Zihan Xi Date: Wed, 29 Jul 2026 09:16:53 +0000 Subject: [PATCH] packet: synchronize pressure clearing with ring reconfiguration 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 diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 5ae0511e89e3..0e1355be89f6 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1315,13 +1315,25 @@ 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); @@ -4305,7 +4317,7 @@ 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) { @@ -4545,14 +4557,14 @@ 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",