[PATCH v3 1/7] net: wget: prevent overwriting reserved memory

[Masahisa Kojima]

This introduces the valid range check to store the received
blocks using lmb. The same logic is implemented in tftp.

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
---
 net/wget.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 73 insertions(+), 7 deletions(-)

diff --git a/net/wget.c b/net/wget.c
index 2dbfeb1a1d..9690e4539c 100644
--- a/net/wget.c
+++ b/net/wget.c
@@ -4,16 +4,20 @@
  * Copyright Duncan Hare <dh at synoia.com> 2017
  */
 
+#include <asm/global_data.h>
 #include <command.h>
 #include <common.h>
 #include <display_options.h>
 #include <env.h>
 #include <image.h>
+#include <lmb.h>
 #include <mapmem.h>
 #include <net.h>
 #include <net/tcp.h>
 #include <net/wget.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 static const char bootfile1[] = "GET ";
 static const char bootfile3[] = " HTTP/1.0\r\n\r\n";
 static const char http_eom[] = "\r\n\r\n";
@@ -55,6 +59,29 @@ static unsigned int retry_tcp_ack_num;	/* TCP retry acknowledge number*/
 static unsigned int retry_tcp_seq_num;	/* TCP retry sequence number */
 static int retry_len;			/* TCP retry length */
 
+static ulong wget_load_size;
+
+/**
+ * wget_init_max_size() - initialize maximum load size
+ *
+ * Return:	0 if success, -1 if fails
+ */
+static int wget_init_load_size(void)
+{
+	struct lmb lmb;
+	phys_size_t max_size;
+
+	lmb_init_and_reserve(&lmb, gd->bd, (void *)gd->fdt_blob);
+
+	max_size = lmb_get_free_size(&lmb, image_load_addr);
+	if (!max_size)
+		return -1;
+
+	wget_load_size = max_size;
+
+	return 0;
+}
+
 /**
  * store_block() - store block in memory
  * @src: source of data
@@ -63,10 +90,25 @@ static int retry_len;			/* TCP retry length */
  */
 static inline int store_block(uchar *src, unsigned int offset, unsigned int len)
 {
+	ulong store_addr = image_load_addr + offset;
 	ulong newsize = offset + len;
 	uchar *ptr;
 
-	ptr = map_sysmem(image_load_addr + offset, len);
+	if (IS_ENABLED(CONFIG_LMB)) {
+		ulong end_addr = image_load_addr + wget_load_size;
+
+		if (!end_addr)
+			end_addr = ULONG_MAX;
+
+		if (store_addr < image_load_addr ||
+		    store_addr + len > end_addr) {
+			puts("\nwget error: ");
+			puts("trying to overwrite reserved memory...\n");
+			return -1;
+		}
+	}
+
+	ptr = map_sysmem(store_addr, len);
 	memcpy(ptr, src, len);
 	unmap_sysmem(ptr);
 
@@ -240,25 +282,39 @@ static void wget_connected(uchar *pkt, unsigned int tcp_seq_num,
 
 			net_boot_file_size = 0;
 
-			if (len > hlen)
-				store_block(pkt + hlen, 0, len - hlen);
+			if (len > hlen) {
+				if (store_block(pkt + hlen, 0, len - hlen) != 0) {
+					wget_loop_state = NETLOOP_FAIL;
+					wget_fail("wget: store error\n", tcp_seq_num, tcp_ack_num, action);
+					net_set_state(NETLOOP_FAIL);
+					return;
+				}
+			}
 
 			debug_cond(DEBUG_WGET,
 				   "wget: Connected Pkt %p hlen %x\n",
 				   pkt, hlen);
 
 			for (i = 0; i < pkt_q_idx; i++) {
+				int err;
+
 				ptr1 = map_sysmem(
 					(phys_addr_t)(pkt_q[i].pkt),
 					pkt_q[i].len);
-				store_block(ptr1,
-					    pkt_q[i].tcp_seq_num -
-					    initial_data_seq_num,
-					    pkt_q[i].len);
+				err = store_block(ptr1,
+						  pkt_q[i].tcp_seq_num -
+						  initial_data_seq_num,
+						  pkt_q[i].len);
 				unmap_sysmem(ptr1);
 				debug_cond(DEBUG_WGET,
 					   "wget: Connctd pkt Q %p len %x\n",
 					   pkt_q[i].pkt, pkt_q[i].len);
+				if (err) {
+					wget_loop_state = NETLOOP_FAIL;
+					wget_fail("wget: store error\n", tcp_seq_num, tcp_ack_num, action);
+					net_set_state(NETLOOP_FAIL);
+					return;
+				}
 			}
 		}
 	}
@@ -330,6 +386,7 @@ static void wget_handler(uchar *pkt, u16 dport,
 				len) != 0) {
 			wget_fail("wget: store error\n",
 				  tcp_seq_num, tcp_ack_num, action);
+			net_set_state(NETLOOP_FAIL);
 			return;
 		}
 
@@ -420,6 +477,15 @@ void wget_start(void)
 	debug_cond(DEBUG_WGET,
 		   "\nwget:Load address: 0x%lx\nLoading: *\b", image_load_addr);
 
+	if (IS_ENABLED(CONFIG_LMB)) {
+		if (wget_init_load_size()) {
+			printf("\nwget error: ");
+			printf("trying to overwrite reserved memory...\n");
+			net_set_state(NETLOOP_FAIL);
+			return;
+		}
+	}
+
 	net_set_timeout_handler(wget_timeout, wget_timeout_handler);
 	tcp_set_tcp_handler(wget_handler);
 
-- 
2.34.1