Re: [PATCH Next] ntfs3: init run lock for extend inode

[Konstantin Komarov <almaz.alexandrovich@paragon-software.com>]

On 9/16/25 07:50, Edward Adam Davis wrote:

> After setting the inode mode of $Extend to a regular file, executing the
> truncate system call will enter the do_truncate() routine, causing the
> run_lock uninitialized error reported by syzbot.
>
> Prior to patch 4e8011ffec79, if the inode mode of $Extend was not set to
> a regular file, the do_truncate() routine would not be entered.
>
> Add the run_lock initialization when loading $Extend.
>
> syzbot reported:
> INFO: trying to register non-static key.
> Call Trace:
>   dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
>   assign_lock_key+0x133/0x150 kernel/locking/lockdep.c:984
>   register_lock_class+0x105/0x320 kernel/locking/lockdep.c:1299
>   __lock_acquire+0x99/0xd20 kernel/locking/lockdep.c:5112
>   lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
>   down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
>   ntfs_set_size+0x140/0x200 fs/ntfs3/inode.c:860
>   ntfs_extend+0x1d9/0x970 fs/ntfs3/file.c:387
>   ntfs_setattr+0x2e8/0xbe0 fs/ntfs3/file.c:808
>
> Fixes: 4e8011ffec79 ("ntfs3: pretend $Extend records as regular files")
> Reported-by: syzbot+bdeb22a4b9a09ab9aa45@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=bdeb22a4b9a09ab9aa45
> Tested-by: syzbot+bdeb22a4b9a09ab9aa45@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.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;

Taken, thanks. Will be sent in the next pull request.

Regards,
Konstantin