!82 syscall review bugfix

Merge pull request !82 from 野生毛霉君/master

fs/vfs/fs_read.c

@@ -141,6 +141,11 @@ ssize_t file_read(struct file *filep, void *buf, size_t nbytes)
 
 ssize_t read(int fd, void *buf, size_t nbytes)
 {
+  if (buf == NULL || nbytes < 0)
+    {
+      set_errno(EINVAL);
+      return VFS_ERROR;
+    }
   /* Did we get a valid file descriptor? */
 
 #if CONFIG_NFILE_DESCRIPTORS > 0

fs/vfs/fs_readlink.c

@@ -44,7 +44,7 @@ ssize_t do_readlink(int dirfd, const char *path, char *buf, size_t bufsize)
       goto errout;
     }
 
-  if (*path == '\0')
+  if (*path == '\0' || buf == NULL || bufsize < 0)
     {
       ret = -EINVAL;
       goto errout;

fs/vfs/fs_select.c

@@ -120,7 +120,7 @@ int do_select(int nfds, fd_set *readfds, fd_set *writefds,
   int ndx;
   int ret;
 
-  if (nfds < 0)
+  if (nfds < 0 || nfds >= FD_SETSIZE)
     {
       set_errno(EINVAL);
       return VFS_ERROR;

fs/vfs/fs_symlink.c

@@ -39,6 +39,10 @@ int follow_symlink(int dirfd, const char *path, struct Vnode **vnode, char **ful
   struct Vnode *newvnode = NULL;
   char pathname[PATH_MAX] = {0};
 
+  if (path == NULL) {
+      return -EINVAL;
+  }
+
   (void)strcpy_s(pathname, PATH_MAX, path);
 
   for (int i = 0; i < CONFIG_FS_MAX_LNK_CNT; i++)