Prevent memory leak while loading smbios data

Author: brunexgeek

README.md

@@ -26,14 +26,18 @@ int main(int argc, char *argv[])
     // Get SMBIOS information using a custom function.
     // An example in C for Windows and Linux can be found
     // in 'smbios_decode.c'.
-    const uint8_t *data = NULL;
+    uint8_t *data = NULL;
     size_t size = 0;
-    load_smbios_data(&data, &size);
+    if (!get_dmi_data("/sys/firmware/dmi/tables", &data, &size))
+        return 1;
 
     // initialize the parser (the desired SMBIOS version is 3.0)
     struct ParserContext context;
     if (smbios_initialize(&context, data, size, SMBIOS_3_0) != SMBERR_OK)
+    {
+        free(data);
         return 1;
+    }
 
     // iterate over the SMBIOS entries
     const struct Entry *entry = NULL;
@@ -42,6 +46,8 @@ int main(int argc, char *argv[])
         // do something with the current entry
     }
 
+    free(data);
+
     return 0;
 }
 ```

smbios_decode.c

@@ -37,7 +37,12 @@ static bool get_dmi_data( uint8_t **buffer, size_t *size )
     if (*buffer == NULL)
         return false;
     // retrieve the SMBIOS table
-    return (*size == GetSystemFirmwareTable(signature, 0, *buffer, *size))
+    if (*size != GetSystemFirmwareTable(signature, 0, *buffer, *size))
+    {
+        free(*buffer);
+        return false;
+    }
+    return true;
 }
 
 #else
@@ -60,15 +65,21 @@ static bool get_dmi_data( const char *path, uint8_t **buffer, size_t *size )
     // read SMBIOS structures
     input = fopen(fileName, "rb");
     if (input == NULL)
+    {
+        free(*buffer);
         return false;
+    }
     fread((char*) *buffer + 32, (size_t) info.st_size, 1, input);
     fclose(input);
 
     // read SMBIOS entry point
     snprintf(fileName, sizeof(fileName), "%s/smbios_entry_point", path);
     input = fopen(fileName, "rb");
     if (input == NULL)
+    {
+        free(*buffer);
         return false;
+    }
     fread((char*) *buffer, 32, 1, input);
     fclose(input);
 
@@ -481,15 +492,15 @@ int main(int argc, char ** argv)
 
     if (!result)
     {
-        fputs("Unable to open SMBIOS tables", stderr);
+        fputs("Unable to open SMBIOS tables\n", stderr);
         return 1;
     }
 
     struct ParserContext parser;
     if (smbios_initialize(&parser, buffer, size, SMBIOS_ANY) == SMBERR_OK)
         printSMBIOS(&parser, stdout);
     else
-        fputs("Invalid SMBIOS data", stderr);
+        fputs("Invalid SMBIOS data\n", stderr);
 
     free(buffer);
     return 0;