f2fs: check filename length in recover_dentry

In current flow, we will get Null return value of f2fs_find_entry in
recover_dentry when name.len is bigger than F2FS_NAME_LEN, and then we
still add this inode into its dir entry.
To avoid this situation, we must check filename length before we use it.

Another point is that we could remove the code of checking filename length
In f2fs_find_entry, because f2fs_lookup will be called previously to ensure of
validity of filename length.

V2:
 o add WARN_ON() as Jaegeuk Kim suggested.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 07ad850..f0b4630 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -190,9 +190,6 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
 	unsigned int max_depth;
 	unsigned int level;
 
-	if (unlikely(namelen > F2FS_NAME_LEN))
-		return NULL;
-
 	if (npages == 0)
 		return NULL;
 
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index a3f4542..4d411a2 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -62,6 +62,12 @@ static int recover_dentry(struct page *ipage, struct inode *inode)
 
 	name.len = le32_to_cpu(raw_inode->i_namelen);
 	name.name = raw_inode->i_name;
+
+	if (unlikely(name.len > F2FS_NAME_LEN)) {
+		WARN_ON(1);
+		err = -ENAMETOOLONG;
+		goto out;
+	}
 retry:
 	de = f2fs_find_entry(dir, &name, &page);
 	if (de && inode->i_ino == le32_to_cpu(de->ino))