Forwarded: [PATCH] ntfs3: initialize run_lock for $Extend inode records

syzbot
2025-10-14T12:53:27Z

Subject: [PATCH] ntfs3: initialize run_lock for $Extend inode records
Author: kartikey406@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Inodes from the $Extend directory (NTFS system metadata files) were not
having their run_lock rwsem initialized. These inodes are assigned
ntfs_file_inode_operations but skip the normal S_ISREG initialization
path where run_lock is initialized.

When operations like truncate are called on these inodes, the code
attempts to acquire the uninitialized run_lock, triggering lockdep
warnings about using non-static keys.

Initialize run_lock for $Extend records to match the initialization done
for regular files.

Reported-by: syzbot+3e58a7dc1a8c00243999@syzkaller.appspotmail.com
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
fs/ntfs3/inode.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 3959f23c487a..180cd984339b 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -472,6 +472,7 @@ static struct inode *ntfs_read_mft(struct inode *inode,
/* Records in $Extend are not a files or general directories. */
inode->i_op = &ntfs_file_inode_operations;
mode = S_IFREG;
+ init_rwsem(&ni->file.run_lock);
} else {
err = -EINVAL;
goto out;
--
2.43.0