fs/mmap: add sanity check

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

fs/mmap/fs_mmap.c

@@ -74,6 +74,13 @@ static int file_mmap_(FAR struct file *filep, FAR void *start,
    */
 
 #ifdef CONFIG_DEBUG_FEATURES
+  /* A flags with MAP_PRIVATE and MAP_SHARED is invalid. */
+
+  if ((flags & MAP_PRIVATE) && (flags & MAP_SHARED))
+    {
+      return -EINVAL;
+    }
+
   /* Fixed mappings and protections are not currently supported.  These
    * options could be supported in the KERNEL build with an MMU, but that
    * logic is not in place.

fs/mmap/fs_munmap.c

@@ -69,6 +69,13 @@ static int file_munmap_(FAR void *start, size_t length, bool kernel)
       mm_map_unlock();
     }
 
+  /* If entry don't find, the start and length is invalid. */
+
+  if (entry == NULL)
+    {
+      return -EINVAL;
+    }
+
   return ret;
 }