From e3ba22907f903f11cd12321c31e7936b8dd1157e Mon Sep 17 00:00:00 2001
From: Peter Harper <peter.harper@raspberrypi.com>
Date: Wed, 11 Jan 2023 18:28:18 +0000
Subject: [PATCH] 3rd-party/lwip/dhcp-server: fix unaligned accesses

In the dhcp server, avoid casting a uint8_t* to uint32_t* when using
ip addresses.
---
 3rd-party/lwip/dhcp-server/dhserver.c | 38 ++++++++++++++++-----------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/3rd-party/lwip/dhcp-server/dhserver.c b/3rd-party/lwip/dhcp-server/dhserver.c
index 7aaf61e27..1ced6025f 100644
--- a/3rd-party/lwip/dhcp-server/dhserver.c
+++ b/3rd-party/lwip/dhcp-server/dhserver.c
@@ -96,11 +96,19 @@ static dhcp_config_t *config = NULL;
 
 char magic_cookie[] = {0x63,0x82,0x53,0x63};
 
+static uint32_t get_addr32(const uint8_t addr[4]) {
+	return PP_HTONL(LWIP_MAKEU32(addr[0],addr[1],addr[2],addr[3]));
+}
+
+static void set_addr32(uint8_t *dst, uint32_t src) {
+	memcpy(dst, &src, 4);
+}
+
 static dhcp_entry_t *entry_by_ip(uint32_t ip)
 {
 	int i;
 	for (i = 0; i < config->num_entry; i++)
-		if (*(uint32_t *)config->entries[i].addr == ip)
+		if (get_addr32(config->entries[i].addr) == ip)
 			return &config->entries[i];
 	return NULL;
 }
@@ -165,7 +173,7 @@ static int fill_options(void *dest,
 	/* dhcp server identifier */
 	*ptr++ = DHCP_SERVERID;
 	*ptr++ = 4;
-	*(uint32_t *)ptr = serverid;
+	set_addr32(ptr, serverid);
 	ptr += 4;
 
 	/* lease time */
@@ -179,7 +187,7 @@ static int fill_options(void *dest,
 	/* subnet mask */
 	*ptr++ = DHCP_SUBNETMASK;
 	*ptr++ = 4;
-	*(uint32_t *)ptr = subnet;
+	set_addr32(ptr, subnet);
 	ptr += 4;
 
 	/* router */
@@ -187,7 +195,7 @@ static int fill_options(void *dest,
 	{
 		*ptr++ = DHCP_ROUTER;
 		*ptr++ = 4;
-		*(uint32_t *)ptr = router;
+		set_addr32(ptr, router);
 		ptr += 4;
 	}
 
@@ -206,7 +214,7 @@ static int fill_options(void *dest,
 	{
 		*ptr++ = DHCP_DNSSERVER;
 		*ptr++ = 4;
-		*(uint32_t *)ptr = dns;
+		set_addr32(ptr, dns);
 		ptr += 4;
 	}
 
@@ -237,7 +245,7 @@ static void udp_recv_proc(void *arg, struct udp_pcb *upcb, struct pbuf *p, const
 			dhcp_data.dp_op = 2; /* reply */
 			dhcp_data.dp_secs = 0;
 			dhcp_data.dp_flags = 0;
-			*(uint32_t *)dhcp_data.dp_yiaddr = *(uint32_t *)entry->addr;
+			set_addr32(dhcp_data.dp_yiaddr, get_addr32(entry->addr));
 			memcpy(dhcp_data.dp_magic, magic_cookie, 4);
 
 			memset(dhcp_data.dp_options, 0, sizeof(dhcp_data.dp_options));
@@ -245,11 +253,11 @@ static void udp_recv_proc(void *arg, struct udp_pcb *upcb, struct pbuf *p, const
 			fill_options(dhcp_data.dp_options,
 				DHCP_OFFER,
 				config->domain,
-				*(uint32_t *)config->dns,
+				get_addr32(config->dns),
 				entry->lease, 
-				*(uint32_t *)config->addr,
-				*(uint32_t *)config->addr, 
-				*(uint32_t *)entry->subnet);
+				get_addr32(config->addr),
+				get_addr32(config->addr),
+				get_addr32(entry->subnet));
 
 			pp = pbuf_alloc(PBUF_TRANSPORT, sizeof(dhcp_data), PBUF_POOL);
 			if (pp == NULL) break;
@@ -270,7 +278,7 @@ static void udp_recv_proc(void *arg, struct udp_pcb *upcb, struct pbuf *p, const
 			if (entry != NULL) free_entry(entry);
 
 			/* 3. find requested ipaddr */
-			entry = entry_by_ip(*(uint32_t *)ptr);
+			entry = entry_by_ip(get_addr32(ptr));
 			if (entry == NULL) break;
 			if (!is_vacant(entry)) break;
 
@@ -287,11 +295,11 @@ static void udp_recv_proc(void *arg, struct udp_pcb *upcb, struct pbuf *p, const
 			fill_options(dhcp_data.dp_options,
 				DHCP_ACK,
 				config->domain,
-				*(uint32_t *)config->dns,
+				get_addr32(config->dns),
 				entry->lease, 
-				*(uint32_t *)config->addr,
-				*(uint32_t *)config->addr, 
-				*(uint32_t *)entry->subnet);
+				get_addr32(config->addr),
+				get_addr32(config->addr), 
+				get_addr32(entry->subnet));
 
 			/* 6. send ACK */
 			pp = pbuf_alloc(PBUF_TRANSPORT, sizeof(dhcp_data), PBUF_POOL);