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 152DDFBF6 for ; Mon, 15 May 2023 17:56:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CD49C433D2; Mon, 15 May 2023 17:56:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173400; bh=GEcvCinZNOGNElHmlU4euET+qrTYDXddU6JnYOlI/WA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PI9D22nN44J1p2r5y7w6ke146lIVOGvadM1qavePHBAFPOaxKTraR14WM5dkxWSNI j/4oFnhW2RSA7zsF1TGYRi5yf7LaPHZzKHl+IKJczPm7z0XGhJJ4JLYcsPP74+HWcz kw58Duk9xS21gc2tTjJvpIV2K5qnVejoyncOEwB8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 083/282] net/packet: annotate accesses to po->xmit Date: Mon, 15 May 2023 18:27:41 +0200 Message-Id: <20230515161724.736823460@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161722.146344674@linuxfoundation.org> References: <20230515161722.146344674@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Eric Dumazet [ Upstream commit b9d83ab8a708f23a4001d60e9d8d0b3be3d9f607 ] po->xmit can be set from setsockopt(PACKET_QDISC_BYPASS), while read locklessly. Use READ_ONCE()/WRITE_ONCE() to avoid potential load/store tearing issues. Fixes: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/packet/af_packet.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 450dc03347725..8636e74557ec2 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -266,7 +266,8 @@ static void packet_cached_dev_reset(struct packet_sock *po) static bool packet_use_direct_xmit(const struct packet_sock *po) { - return po->xmit == packet_direct_xmit; + /* Paired with WRITE_ONCE() in packet_setsockopt() */ + return READ_ONCE(po->xmit) == packet_direct_xmit; } static u16 packet_pick_tx_queue(struct sk_buff *skb) @@ -2799,7 +2800,8 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) packet_inc_pending(&po->tx_ring); status = TP_STATUS_SEND_REQUEST; - err = po->xmit(skb); + /* Paired with WRITE_ONCE() in packet_setsockopt() */ + err = READ_ONCE(po->xmit)(skb); if (unlikely(err != 0)) { if (err > 0) err = net_xmit_errno(err); @@ -3002,7 +3004,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) virtio_net_hdr_set_proto(skb, &vnet_hdr); } - err = po->xmit(skb); + /* Paired with WRITE_ONCE() in packet_setsockopt() */ + err = READ_ONCE(po->xmit)(skb); if (unlikely(err != 0)) { if (err > 0) err = net_xmit_errno(err); @@ -3949,7 +3952,8 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv if (copy_from_user(&val, optval, sizeof(val))) return -EFAULT; - po->xmit = val ? packet_direct_xmit : dev_queue_xmit; + /* Paired with all lockless reads of po->xmit */ + WRITE_ONCE(po->xmit, val ? packet_direct_xmit : dev_queue_xmit); return 0; } default: -- 2.39.2