udf: Implement searching for directory entry using new iteration code

Implement searching for directory entry - udf_fiiter_find_entry() -
using new directory iteration code.

Reported-by: syzbot+69c9fdccc6dd08961d34@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 78bc4bb..145883d 100644 (file)
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -141,6 +141,73 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
 }
 
 /**
+ * udf_fiiter_find_entry - find entry in given directory.
+ *
+ * @dir:       directory inode to search in
+ * @child:     qstr of the name
+ * @iter:      iter to use for searching
+ *
+ * This function searches in the directory @dir for a file name @child. When
+ * found, @iter points to the position in the directory with given entry.
+ *
+ * Returns 0 on success, < 0 on error (including -ENOENT).
+ */
+static int udf_fiiter_find_entry(struct inode *dir, const struct qstr *child,
+                                struct udf_fileident_iter *iter)
+{
+       int flen;
+       unsigned char *fname = NULL;
+       struct super_block *sb = dir->i_sb;
+       int isdotdot = child->len == 2 &&
+               child->name[0] == '.' && child->name[1] == '.';
+       int ret;
+
+       fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
+       if (!fname)
+               return -ENOMEM;
+
+       for (ret = udf_fiiter_init(iter, dir, 0);
+            !ret && iter->pos < dir->i_size;
+            ret = udf_fiiter_advance(iter)) {
+               if (iter->fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
+                       if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
+                               continue;
+               }
+
+               if (iter->fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
+                       if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
+                               continue;
+               }
+
+               if ((iter->fi.fileCharacteristics & FID_FILE_CHAR_PARENT) &&
+                   isdotdot)
+                       goto out_ok;
+
+               if (!iter->fi.lengthFileIdent)
+                       continue;
+
+               flen = udf_get_filename(sb, iter->name,
+                               iter->fi.lengthFileIdent, fname, UDF_NAME_LEN);
+               if (flen < 0) {
+                       ret = flen;
+                       goto out_err;
+               }
+
+               if (udf_match(flen, fname, child->len, child->name))
+                       goto out_ok;
+       }
+       if (!ret)
+               ret = -ENOENT;
+
+out_err:
+       udf_fiiter_release(iter);
+out_ok:
+       kfree(fname);
+
+       return ret;
+}
+
+/**
  * udf_find_entry - find entry in given directory.
  *
  * @dir:       directory inode to search in