From 290b1bfd8597c710bd83b6bc59e2cb5d21a06077 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Thu, 2 May 2024 07:46:14 +0000
Subject: [PATCH] Revert "net: dev: Convert sa_data to flexible array in struct
 sockaddr"

This reverts commit fd84a5fae03c0a6ca66d6d7eb9f473b2c7957c21 which is
commit b5f0de6df6dce8d641ef58ef7012f3304dffb9a1 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Iecd4acaa6f3d416b1fe7b928d3b4f069bf61861e
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
---
 include/linux/socket.h |  5 +----
 net/core/dev.c         |  2 +-
 net/core/dev_ioctl.c   |  2 +-
 net/packet/af_packet.c | 10 +++++-----
 4 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index d79efd026880..b3c58042bd25 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -33,10 +33,7 @@ typedef __kernel_sa_family_t	sa_family_t;
 
 struct sockaddr {
 	sa_family_t	sa_family;	/* address family, AF_xxx	*/
-	union {
-		char sa_data_min[14];		/* Minimum 14 bytes of protocol address	*/
-		DECLARE_FLEX_ARRAY(char, sa_data);
-	};
+	char		sa_data[14];	/* 14 bytes of protocol address	*/
 };
 
 struct linger {
diff --git a/net/core/dev.c b/net/core/dev.c
index 3102191d0877..06600fa3f94c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8868,7 +8868,7 @@ EXPORT_SYMBOL(dev_set_mac_address_user);
 
 int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
 {
-	size_t size = sizeof(sa->sa_data_min);
+	size_t size = sizeof(sa->sa_data);
 	struct net_device *dev;
 	int ret = 0;
 
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 5cdbfbf9a7dc..7674bb9f3076 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -342,7 +342,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
 		if (ifr->ifr_hwaddr.sa_family != dev->type)
 			return -EINVAL;
 		memcpy(dev->broadcast, ifr->ifr_hwaddr.sa_data,
-		       min(sizeof(ifr->ifr_hwaddr.sa_data_min),
+		       min(sizeof(ifr->ifr_hwaddr.sa_data),
 			   (size_t)dev->addr_len));
 		call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
 		return 0;
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c3117350f5fb..51882f07ef70 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3284,7 +3284,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
 			    int addr_len)
 {
 	struct sock *sk = sock->sk;
-	char name[sizeof(uaddr->sa_data_min) + 1];
+	char name[sizeof(uaddr->sa_data) + 1];
 
 	/*
 	 *	Check legality
@@ -3295,8 +3295,8 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
 	/* uaddr->sa_data comes from the userspace, it's not guaranteed to be
 	 * zero-terminated.
 	 */
-	memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data_min));
-	name[sizeof(uaddr->sa_data_min)] = 0;
+	memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));
+	name[sizeof(uaddr->sa_data)] = 0;
 
 	return packet_do_bind(sk, name, 0, 0);
 }
@@ -3566,11 +3566,11 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
 		return -EOPNOTSUPP;
 
 	uaddr->sa_family = AF_PACKET;
-	memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data_min));
+	memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data));
 	rcu_read_lock();
 	dev = dev_get_by_index_rcu(sock_net(sk), READ_ONCE(pkt_sk(sk)->ifindex));
 	if (dev)
-		strscpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data_min));
+		strscpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data));
 	rcu_read_unlock();
 
 	return sizeof(*uaddr);