Re: [syzbot] [ntfs3?] KMSAN: uninit-value in ntfs_iomap_begin

[Edward Adam Davis]

#syz test

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 6e65066ebcc1..eac421cf98a8 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -822,6 +822,11 @@ static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		return err;
 	}
 
+	if (!clen) {
+		/* broken file? */
+		return -EINVAL;
+	}
+
 	if (lcn == EOF_LCN) {
 		/* request out of file. */
 		if (flags & IOMAP_REPORT) {
@@ -855,11 +860,6 @@ static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		return 0;
 	}
 
-	if (!clen) {
-		/* broken file? */
-		return -EINVAL;
-	}
-
 	iomap->bdev = inode->i_sb->s_bdev;
 	iomap->offset = offset;
 	iomap->length = ((loff_t)clen << cluster_bits) - off;