Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 67b2dc7..2ce85e5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -343,7 +343,7 @@
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
 		return;
-	mtu = tcp_sk(sk)->mtu_info;
+	mtu = READ_ONCE(tcp_sk(sk)->mtu_info);
 	dst = inet_csk_update_pmtu(sk, mtu);
 	if (!dst)
 		return;
@@ -512,7 +512,7 @@
 			if (sk->sk_state == TCP_LISTEN)
 				goto out;
 
-			tp->mtu_info = info;
+			WRITE_ONCE(tp->mtu_info, info);
 			if (!sock_owned_by_user(sk)) {
 				tcp_v4_mtu_reduced(sk);
 			} else {
@@ -1077,9 +1077,18 @@
 
 	key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen);
 	if (key) {
-		/* Pre-existing entry - just update that one. */
+		/* Pre-existing entry - just update that one.
+		 * Note that the key might be used concurrently.
+		 */
 		memcpy(key->key, newkey, newkeylen);
-		key->keylen = newkeylen;
+
+		/* Pairs with READ_ONCE() in tcp_md5_hash_key().
+		 * Also note that a reader could catch new key->keylen value
+		 * but old key->key[], this is the reason we use __GFP_ZERO
+		 * at sock_kmalloc() time below these lines.
+		 */
+		WRITE_ONCE(key->keylen, newkeylen);
+
 		return 0;
 	}
 
@@ -1095,7 +1104,7 @@
 		rcu_assign_pointer(tp->md5sig_info, md5sig);
 	}
 
-	key = sock_kmalloc(sk, sizeof(*key), gfp);
+	key = sock_kmalloc(sk, sizeof(*key), gfp | __GFP_ZERO);
 	if (!key)
 		return -ENOMEM;
 	if (!tcp_alloc_md5sig_pool()) {
@@ -1648,6 +1657,7 @@
 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
 {
 	u32 limit = READ_ONCE(sk->sk_rcvbuf) + READ_ONCE(sk->sk_sndbuf);
+	u32 tail_gso_size, tail_gso_segs;
 	struct skb_shared_info *shinfo;
 	const struct tcphdr *th;
 	struct tcphdr *thtail;
@@ -1655,6 +1665,7 @@
 	unsigned int hdrlen;
 	bool fragstolen;
 	u32 gso_segs;
+	u32 gso_size;
 	int delta;
 
 	/* In case all data was pulled from skb frags (in __pskb_pull_tail()),
@@ -1680,13 +1691,6 @@
 	 */
 	th = (const struct tcphdr *)skb->data;
 	hdrlen = th->doff * 4;
-	shinfo = skb_shinfo(skb);
-
-	if (!shinfo->gso_size)
-		shinfo->gso_size = skb->len - hdrlen;
-
-	if (!shinfo->gso_segs)
-		shinfo->gso_segs = 1;
 
 	tail = sk->sk_backlog.tail;
 	if (!tail)
@@ -1709,13 +1713,22 @@
 		goto no_coalesce;
 
 	__skb_pull(skb, hdrlen);
-	if (skb_try_coalesce(tail, skb, &fragstolen, &delta)) {
-		thtail->window = th->window;
 
+	shinfo = skb_shinfo(skb);
+	gso_size = shinfo->gso_size ?: skb->len;
+	gso_segs = shinfo->gso_segs ?: 1;
+
+	shinfo = skb_shinfo(tail);
+	tail_gso_size = shinfo->gso_size ?: (tail->len - hdrlen);
+	tail_gso_segs = shinfo->gso_segs ?: 1;
+
+	if (skb_try_coalesce(tail, skb, &fragstolen, &delta)) {
 		TCP_SKB_CB(tail)->end_seq = TCP_SKB_CB(skb)->end_seq;
 
-		if (after(TCP_SKB_CB(skb)->ack_seq, TCP_SKB_CB(tail)->ack_seq))
+		if (likely(!before(TCP_SKB_CB(skb)->ack_seq, TCP_SKB_CB(tail)->ack_seq))) {
 			TCP_SKB_CB(tail)->ack_seq = TCP_SKB_CB(skb)->ack_seq;
+			thtail->window = th->window;
+		}
 
 		/* We have to update both TCP_SKB_CB(tail)->tcp_flags and
 		 * thtail->fin, so that the fast path in tcp_rcv_established()
@@ -1735,11 +1748,8 @@
 		}
 
 		/* Not as strict as GRO. We only need to carry mss max value */
-		skb_shinfo(tail)->gso_size = max(shinfo->gso_size,
-						 skb_shinfo(tail)->gso_size);
-
-		gso_segs = skb_shinfo(tail)->gso_segs + shinfo->gso_segs;
-		skb_shinfo(tail)->gso_segs = min_t(u32, gso_segs, 0xFFFF);
+		shinfo->gso_size = max(gso_size, tail_gso_size);
+		shinfo->gso_segs = min_t(u32, gso_segs + tail_gso_segs, 0xFFFF);
 
 		sk->sk_backlog.len += delta;
 		__NET_INC_STATS(sock_net(sk),
@@ -2149,13 +2159,14 @@
 	struct tcp_iter_state *st = seq->private;
 	struct net *net = seq_file_net(seq);
 	struct inet_listen_hashbucket *ilb;
+	struct hlist_nulls_node *node;
 	struct sock *sk = cur;
 
 	if (!sk) {
 get_head:
 		ilb = &tcp_hashinfo.listening_hash[st->bucket];
 		spin_lock(&ilb->lock);
-		sk = sk_head(&ilb->head);
+		sk = sk_nulls_head(&ilb->nulls_head);
 		st->offset = 0;
 		goto get_sk;
 	}
@@ -2163,9 +2174,9 @@
 	++st->num;
 	++st->offset;
 
-	sk = sk_next(sk);
+	sk = sk_nulls_next(sk);
 get_sk:
-	sk_for_each_from(sk) {
+	sk_nulls_for_each_from(sk, node) {
 		if (!net_eq(sock_net(sk), net))
 			continue;
 		if (sk->sk_family == afinfo->family)
@@ -2293,6 +2304,7 @@
 static void *tcp_seek_last_pos(struct seq_file *seq)
 {
 	struct tcp_iter_state *st = seq->private;
+	int bucket = st->bucket;
 	int offset = st->offset;
 	int orig_num = st->num;
 	void *rc = NULL;
@@ -2303,7 +2315,7 @@
 			break;
 		st->state = TCP_SEQ_STATE_LISTENING;
 		rc = listening_get_next(seq, NULL);
-		while (offset-- && rc)
+		while (offset-- && rc && bucket == st->bucket)
 			rc = listening_get_next(seq, rc);
 		if (rc)
 			break;
@@ -2314,7 +2326,7 @@
 		if (st->bucket > tcp_hashinfo.ehash_mask)
 			break;
 		rc = established_get_first(seq);
-		while (offset-- && rc)
+		while (offset-- && rc && bucket == st->bucket)
 			rc = established_get_next(seq, rc);
 	}