From: Lidong Chen <lidong.chen@oracle.com>
Date: Wed, 22 Jan 2025 18:04:42 +0000
Subject: net: Use safe math macros to prevent overflows

Replace direct arithmetic operations with macros from include/grub/safemath.h
to prevent potential overflow issues when calculating the memory sizes.

Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Conflicts:
	grub-core/net/bootp.c
	grub-core/net/net.c
---
 grub-core/net/bootp.c                  | 16 +++++++++++--
 grub-core/net/dns.c                    |  9 ++++++-
 grub-core/net/drivers/ieee1275/ofnet.c | 20 ++++++++++++++--
 grub-core/net/net.c                    | 43 +++++++++++++++++++++++++++-------
 4 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/grub-core/net/bootp.c b/grub-core/net/bootp.c
index 563d333..3370c76 100644
--- a/grub-core/net/bootp.c
+++ b/grub-core/net/bootp.c
@@ -25,6 +25,7 @@
 #include <grub/net/netbuff.h>
 #include <grub/net/udp.h>
 #include <grub/datetime.h>
+#include <grub/safemath.h>
 #include <grub/time.h>
 #include <grub/list.h>
 
@@ -1481,6 +1482,7 @@ grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
   unsigned num;
   const grub_uint8_t *ptr;
   grub_uint8_t taglength;
+  grub_uint8_t len;
 
   if (argc < 4)
     return grub_error (GRUB_ERR_BAD_ARGUMENT,
@@ -1522,7 +1524,12 @@ grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
   if (grub_strcmp (args[3], "string") == 0)
     {
       grub_err_t err = GRUB_ERR_NONE;
-      char *val = grub_malloc (taglength + 1);
+      char *val;
+
+      if (grub_add (taglength, 1, &len))
+	return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("tag length overflow"));
+
+      val = grub_malloc (len);
       if (!val)
 	return grub_errno;
       grub_memcpy (val, ptr, taglength);
@@ -1555,7 +1562,12 @@ grub_cmd_dhcpopt (struct grub_command *cmd __attribute__ ((unused)),
   if (grub_strcmp (args[3], "hex") == 0)
     {
       grub_err_t err = GRUB_ERR_NONE;
-      char *val = grub_malloc (2 * taglength + 1);
+      char *val;
+
+      if (grub_mul (taglength, 2, &len) || grub_add (len, 1, &len))
+	return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("tag length overflow"));
+
+      val = grub_malloc (len);
       int i;
       if (!val)
 	return grub_errno;
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
index fcc09aa..39b0c46 100644
--- a/grub-core/net/dns.c
+++ b/grub-core/net/dns.c
@@ -224,10 +224,17 @@ get_name (const grub_uint8_t *name_at, const grub_uint8_t *head,
 {
   int length;
   char *ret;
+  int len;
 
   if (!check_name_real (name_at, head, tail, NULL, &length, NULL))
     return NULL;
-  ret = grub_malloc (length + 1);
+
+  if (grub_add (length, 1, &len))
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("name length overflow"));
+      return NULL;
+    }
+  ret = grub_malloc (len);
   if (!ret)
     return NULL;
   if (!check_name_real (name_at, head, tail, NULL, NULL, ret))
diff --git a/grub-core/net/drivers/ieee1275/ofnet.c b/grub-core/net/drivers/ieee1275/ofnet.c
index 78f03df..c35b107 100644
--- a/grub-core/net/drivers/ieee1275/ofnet.c
+++ b/grub-core/net/drivers/ieee1275/ofnet.c
@@ -22,6 +22,7 @@
 #include <grub/net.h>
 #include <grub/time.h>
 #include <grub/i18n.h>
+#include <grub/safemath.h>
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
@@ -391,6 +392,7 @@ search_net_devices (struct grub_ieee1275_devalias *alias)
   grub_uint8_t *pprop;
   char *shortname;
   char need_suffix = 1;
+  grub_size_t sz;
 
   if (grub_strcmp (alias->type, "network") != 0)
     return 0;
@@ -448,9 +450,23 @@ search_net_devices (struct grub_ieee1275_devalias *alias)
   }
 
   if (need_suffix)
-    ofdata->path = grub_malloc (grub_strlen (alias->path) + sizeof (SUFFIX));
+    {
+      if (grub_add (grub_strlen (alias->path), sizeof (SUFFIX), &sz))
+	{
+	  grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow detected while obatining size of ofdata path"));
+	  grub_print_error ();
+	  return 0;
+	}
+    }
   else
-    ofdata->path = grub_malloc (grub_strlen (alias->path) + 1);
+    {
+      if (grub_add (grub_strlen (alias->path), 1, &sz))
+	{
+	  grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow detected while obatining size of ofdata path"));
+	  grub_print_error ();
+	  return 0;
+	}
+    }
   if (!ofdata->path)
     {
       grub_print_error ();
diff --git a/grub-core/net/net.c b/grub-core/net/net.c
index bdf2445..465f909 100644
--- a/grub-core/net/net.c
+++ b/grub-core/net/net.c
@@ -32,6 +32,7 @@
 #include <grub/loader.h>
 #include <grub/bufio.h>
 #include <grub/kernel.h>
+#include <grub/safemath.h>
 #ifdef GRUB_MACHINE_EFI
 #include <grub/net/efi.h>
 #endif
@@ -209,6 +210,7 @@ grub_net_ipv6_get_slaac (struct grub_net_card *card,
 {
   struct grub_net_slaac_mac_list *slaac;
   char *ptr;
+  grub_size_t sz;
 
   for (slaac = card->slaac_list; slaac; slaac = slaac->next)
     if (grub_net_hwaddr_cmp (&slaac->address, hwaddr) == 0)
@@ -218,9 +220,16 @@ grub_net_ipv6_get_slaac (struct grub_net_card *card,
   if (!slaac)
     return NULL;
 
-  slaac->name = grub_malloc (grub_strlen (card->name)
-			     + GRUB_NET_MAX_STR_HWADDR_LEN
-			     + sizeof (":slaac"));
+  if (grub_add (grub_strlen (card->name),
+      (GRUB_NET_MAX_STR_HWADDR_LEN + sizeof (":slaac")), &sz))
+    {
+      grub_free (slaac);
+      grub_error (GRUB_ERR_OUT_OF_RANGE,
+		  "overflow detected while obtaining size of slaac name");
+      return NULL;
+    }
+
+  slaac->name = grub_malloc (sz);
   ptr = grub_stpcpy (slaac->name, card->name);
   if (grub_net_hwaddr_cmp (&card->default_address, hwaddr) != 0)
     {
@@ -291,6 +300,7 @@ grub_net_ipv6_get_link_local (struct grub_net_card *card,
   char *name;
   char *ptr;
   grub_net_network_level_address_t addr;
+  grub_size_t sz;
 
   addr.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV6;
   addr.ipv6[0] = grub_cpu_to_be64_compile_time (0xfe80ULL << 48);
@@ -305,9 +315,14 @@ grub_net_ipv6_get_link_local (struct grub_net_card *card,
       return inf;
   }
 
-  name = grub_malloc (grub_strlen (card->name)
-		      + GRUB_NET_MAX_STR_HWADDR_LEN
-		      + sizeof (":link"));
+  if (grub_add (grub_strlen (card->name),
+      (GRUB_NET_MAX_STR_HWADDR_LEN + sizeof (":link")), &sz))
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE,
+		  "overflow detected while obtaining size of link name");
+      return NULL;
+    }
+  name = grub_malloc (sz);
   if (!name)
     return NULL;
 
@@ -1510,9 +1525,15 @@ grub_net_open_real (const char *name)
 	  if (grub_strchr (port_start + 1, ':'))
 	    {
 	      int iplen = grub_strlen (server);
+	      grub_size_t sz;
 
 	      /* Bracket bare IPv6 addr. */
-	      host = grub_malloc (iplen + 3);
+	      if (grub_add (iplen, 3, &sz))
+		{
+		  grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow detected while obtaining length of host"));
+		  return NULL;
+		}
+	      host = grub_malloc (sz);
 	      if (!host)
                 return NULL;
 
@@ -1767,6 +1788,7 @@ grub_env_set_net_property (const char *intername, const char *suffix,
 {
   char *varname, *varvalue;
   char *ptr;
+  grub_size_t sz;
 
   varname = grub_xasprintf ("net_%s_%s", intername, suffix);
   if (!varname)
@@ -1774,7 +1796,12 @@ grub_env_set_net_property (const char *intername, const char *suffix,
   for (ptr = varname; *ptr; ptr++)
     if (*ptr == ':')
       *ptr = '_';
-  varvalue = grub_malloc (len + 1);
+  if (grub_add (len, 1, &sz))
+    {
+      grub_free (varname);
+      return grub_error (GRUB_ERR_OUT_OF_RANGE, "overflow detected while obtaining the size of an env variable");
+    }
+  varvalue = grub_malloc (sz);
   if (!varvalue)
     {
       grub_free (varname);