This fix has been submitted upstream as part of a combined patch
which has fixes for CR15758982(027.7118090.hr_filesys.patch) and this CR(16439911).
This can be found in the following location.
https://sourceforge.net/p/net-snmp/patches/1287/. 

This patch has not been accepted yet. 
--- net-snmp-5.4.1.old/agent/mibgroup/host/hr_filesys.c	2014-07-15 01:53:05.131000348 -0700
+++ net-snmp-5.4.1/agent/mibgroup/host/hr_filesys.c	2014-07-15 01:48:04.221278640 -0700
@@ -698,20 +698,25 @@
 static int 
 load_mnttab_cache_solaris()
 {
-    char buf[512] = {NULL};
+    char buf[MNT_LINE_MAX] = {NULL};
     int i = 0;
     struct stat file_stat;
     const char **cpp;
-    char *ch;
+    char *ch, *token_ptr;
     int token_flag = 0;
     int skip_flag = 0;
     int ignore_flag = 0;
     int j = 0;
     int lines = 0;
     int ret = 0;
+    int chk_mnt = -1;
     HRFS_index = 0;
 
-    stat(ETC_MNTTAB, &file_stat);
+    if(stat(ETC_MNTTAB, &file_stat) != 0)
+    {
+        DEBUGMSGTL(("host/hr_filesys", "stat failed for mnttab.\n"));
+        return -1;
+    }
     if (last_access == -1 || last_access != file_stat.st_mtime) {
         fp = fopen(ETC_MNTTAB, "r");
         if(fp == NULL)
@@ -731,7 +736,7 @@
              * which determines the valid entries.
              */
 
-            ch = strtok(buf, " \t");
+            ch = strtok_r(buf, " \t", &token_ptr);
             while (ch != NULL) {
                 j++;
                 if(j == 3) {
@@ -745,7 +750,7 @@
                 }
                 if(token_flag)
                     break;
-                ch = strtok(NULL, " \t");
+                ch = strtok_r(NULL, " \t", &token_ptr);
              }
              if(!skip_flag)
                  lines++;
@@ -765,25 +770,43 @@
             free(HRFS_list);
             return -1;
         }
-
-        while (i < fscount) {
-            if (getmntent(fp, &HRFS_entry_struct) == 0) {
-                 for (cpp = HRFS_ignores; *cpp != NULL; ++cpp) {
-                     if (!strcmp(HRFS_entry_struct.HRFS_type, *cpp)) {
-                         ignore_flag = 1;
-                         break;
-                     }
+        while ((chk_mnt = getmntent(fp, &HRFS_entry_struct)) != -1) {
+             if(chk_mnt != 0)
+                 continue;
+             for (cpp = HRFS_ignores; *cpp != NULL; ++cpp) {
+                 if (!strcmp(HRFS_entry_struct.mnt_fstype, *cpp)) {
+                     ignore_flag = 1;
+                     break;
                  }
-
-                 if(!ignore_flag) {
-                     HRFS_list[i].mnt_special = strdup(HRFS_entry_struct.mnt_special);
-                     HRFS_list[i].mnt_mountp = strdup(HRFS_entry_struct.mnt_mountp);
-                     HRFS_list[i].mnt_fstype = strdup(HRFS_entry_struct.mnt_fstype);
-                     HRFS_list[i].mnt_mntopts = strdup(HRFS_entry_struct.mnt_mntopts);
-                     i++;
+             }
+             if(!ignore_flag) {
+                 if(i >= fscount)
+                 {
+                    DEBUGMSGTL(("host/hr_filesys","increasing cachesize from %d to %d",fscount,i+1));
+                    HRFS_list = realloc(HRFS_list, sizeof(struct mnttab) * (i+1));
+                    fscount = i+1;
+                    if(HRFS_list == NULL)
+                    {
+                        DEBUGMSGTL(("host/hr_filesys","\nrealloc failed for mnttab cache.\n"));
+                        return -1;
+                    }
                  }
-
-                 ignore_flag = 0;
+                 HRFS_list[i].mnt_special = strdup(HRFS_entry_struct.mnt_special);
+                 HRFS_list[i].mnt_mountp = strdup(HRFS_entry_struct.mnt_mountp);
+                 HRFS_list[i].mnt_fstype = strdup(HRFS_entry_struct.mnt_fstype);
+                 HRFS_list[i].mnt_mntopts = strdup(HRFS_entry_struct.mnt_mntopts);
+                 i++;
+             }
+             ignore_flag = 0;
+        }
+        if(i < fscount)
+        {
+            DEBUGMSGTL(("host/hr_filesys","\ndecreasing cachesize from %d to %d\n",fscount,i));
+            HRFS_list = realloc(HRFS_list, sizeof(struct mnttab) * i );
+            if(HRFS_list == NULL)
+            {
+                DEBUGMSGTL(("host/hr_filesys","\nrealloc failed for mnttab cache.\n"));
+                return -1;
             }
         }
 
@@ -925,19 +948,19 @@
         HRFS_entry = NULL;
     }
 #else
-    int i = 0;
     if (fp != NULL)
         fclose(fp);
     fp = NULL;
 
 #ifdef solaris2
-while (i < fscount) {
-    free(HRFS_list[i].mnt_special);
-    free(HRFS_list[i].mnt_mountp);
-    free(HRFS_list[i].mnt_fstype);
-    free(HRFS_list[i].mnt_mntopts);
-    i++;
-}
+    int i = 0;
+    while (i < fscount) {
+        free(HRFS_list[i].mnt_special);
+        free(HRFS_list[i].mnt_mountp);
+        free(HRFS_list[i].mnt_fstype);
+        free(HRFS_list[i].mnt_mntopts);
+        i++;
+    }
     if (HRFS_list != NULL)
         free(HRFS_list);
     last_access = -1;