This is a note to let you know that I've just added the patch titled
net/packet: annotate accesses to po->xmit
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-packet-annotate-accesses-to-po-xmit.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2c9c66b9bab19c1821029bc8d47f5f50764306b0
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu Mar 16 01:10:06 2023 +0000
net/packet: annotate accesses to po->xmit
[ 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 <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7f9f2d0ef0e62..1b3c54e0fbdfb 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -271,7 +271,8 @@ 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)
@@ -2828,7 +2829,8 @@ 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);
@@ -3031,7 +3033,8 @@ 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);
@@ -3976,7 +3979,8 @@ packet_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval,
if (copy_from_sockptr(&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:
