[PATCH V2] ntfs3: Fix WARNING in ntfs_extend_initialized_size

[Edward Adam Davis]

Syzbot reported a WARNING in ntfs_extend_initialized_size.
The data type of in->i_valid and to is u64 in ntfs_file_mmap().
If their values are greater than LLONG_MAX, overflow will occur because
the data types of the parameters valid and new_valid corresponding to
the function ntfs_extend_initialized_size() are loff_t.

Before calling ntfs_extend_initialized_size() in the ntfs_file_mmap(),
the "ni->i_valid < to" has been determined, so the same WARN_ON determination
is not required in ntfs_extend_initialized_size(). 
Just execute the ntfs_extend_initialized_size() in ntfs_extend() to make
a WARN_ON check.

Reported-and-tested-by: syzbot+e37dd1dfc814b10caa55@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=e37dd1dfc814b10caa55
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
V1 -> V2: typo for ni->i_valid

 fs/ntfs3/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
index 6202895a4542..c42454a62314 100644
--- a/fs/ntfs3/file.c
+++ b/fs/ntfs3/file.c
@@ -178,7 +178,6 @@ static int ntfs_extend_initialized_size(struct file *file,
 	}
 
 	WARN_ON(is_compressed(ni));
-	WARN_ON(valid >= new_valid);
 
 	for (;;) {
 		u32 zerofrom, len;
@@ -400,6 +399,7 @@ static int ntfs_extend(struct inode *inode, loff_t pos, size_t count,
 	}
 
 	if (extend_init && !is_compressed(ni)) {
+		WARN_ON(ni->i_valid >= pos);
 		err = ntfs_extend_initialized_size(file, ni, ni->i_valid, pos);
 		if (err)
 			goto out;
-- 
2.43.0