Merge branch 'inet-more-data-race-fixes'

Eric Dumazet says:

====================
inet: more data-race fixes

This series fixes some existing data-races on inet fields:

inet->mc_ttl, inet->pmtudisc, inet->tos, inet->uc_index,
inet->mc_index and inet->mc_addr.

While fixing them, we convert eight socket options
to lockless implementation.

v2: addressed David Ahern feedback on ("inet: implement lockless IP_TOS")
    Added David Reviewed-by: tag on other patches.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 8 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c3ff984b6354..7f7724beca33 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -750,7 +750,7 @@ int __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
 	case ICMP_DEST_UNREACH:
 		if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
 			ipv4_sk_update_pmtu(skb, sk, info);
-			if (inet->pmtudisc != IP_PMTUDISC_DONT) {
+			if (READ_ONCE(inet->pmtudisc) != IP_PMTUDISC_DONT) {
 				err = EMSGSIZE;
 				harderr = 1;
 				break;
@@ -1055,6 +1055,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
 	struct sk_buff *skb;
 	struct ip_options_data opt_copy;
+	int uc_index;
 
 	if (len > 0xFFFF)
 		return -EMSGSIZE;
@@ -1173,25 +1174,26 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	if (scope == RT_SCOPE_LINK)
 		connected = 0;
 
+	uc_index = READ_ONCE(inet->uc_index);
 	if (ipv4_is_multicast(daddr)) {
 		if (!ipc.oif || netif_index_is_l3_master(sock_net(sk), ipc.oif))
-			ipc.oif = inet->mc_index;
+			ipc.oif = READ_ONCE(inet->mc_index);
 		if (!saddr)
-			saddr = inet->mc_addr;
+			saddr = READ_ONCE(inet->mc_addr);
 		connected = 0;
 	} else if (!ipc.oif) {
-		ipc.oif = inet->uc_index;
-	} else if (ipv4_is_lbcast(daddr) && inet->uc_index) {
+		ipc.oif = uc_index;
+	} else if (ipv4_is_lbcast(daddr) && uc_index) {
 		/* oif is set, packet is to local broadcast and
 		 * uc_index is set. oif is most likely set
 		 * by sk_bound_dev_if. If uc_index != oif check if the
 		 * oif is an L3 master and uc_index is an L3 slave.
 		 * If so, we want to allow the send using the uc_index.
 		 */
-		if (ipc.oif != inet->uc_index &&
+		if (ipc.oif != uc_index &&
 		    ipc.oif == l3mdev_master_ifindex_by_index(sock_net(sk),
-							      inet->uc_index)) {
-			ipc.oif = inet->uc_index;
+							      uc_index)) {
+			ipc.oif = uc_index;
 		}
 	}