Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/unix/diag.c b/net/unix/diag.c
index 384c84e..9ff64f9 100644
--- a/net/unix/diag.c
+++ b/net/unix/diag.c
@@ -1,16 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/types.h>
 #include <linux/spinlock.h>
 #include <linux/sock_diag.h>
 #include <linux/unix_diag.h>
 #include <linux/skbuff.h>
 #include <linux/module.h>
+#include <linux/uidgid.h>
 #include <net/netlink.h>
 #include <net/af_unix.h>
 #include <net/tcp_states.h>
+#include <net/sock.h>
 
 static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
 {
-	struct unix_address *addr = unix_sk(sk)->addr;
+	/* might or might not have unix_table_lock */
+	struct unix_address *addr = smp_load_acquire(&unix_sk(sk)->addr);
 
 	if (!addr)
 		return 0;
@@ -109,6 +113,12 @@
 	return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);
 }
 
+static int sk_diag_dump_uid(struct sock *sk, struct sk_buff *nlskb)
+{
+	uid_t uid = from_kuid_munged(sk_user_ns(nlskb->sk), sock_i_uid(sk));
+	return nla_put(nlskb, UNIX_DIAG_UID, sizeof(uid_t), &uid);
+}
+
 static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
 		u32 portid, u32 seq, u32 flags, int sk_ino)
 {
@@ -155,6 +165,10 @@
 	if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, sk->sk_shutdown))
 		goto out_nlmsg_trim;
 
+	if ((req->udiag_show & UDIAG_SHOW_UID) &&
+	    sk_diag_dump_uid(sk, skb))
+		goto out_nlmsg_trim;
+
 	nlmsg_end(skb, nlh);
 	return 0;