Re: possible fix (linux-ntfs3)

[syzbot <syzbot+8c652f14a0fde76ff11d@syzkaller.appspotmail.com>]

> #syz test: https://github.com/Paragon-Software-Group/linux-ntfs3.git master

This crash does not have a reproducer. I cannot test it.

>
> diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
> index 4fdcb5177ea1..eb935d4180c0 100644
> --- a/fs/ntfs3/file.c
> +++ b/fs/ntfs3/file.c
> @@ -1314,7 +1314,14 @@ static int ntfs_file_release(struct inode *inode, struct file *file)
>  	/* If we are last writer on the inode, drop the block reservation. */
>  	if (sbi->options->prealloc &&
>  	    ((file->f_mode & FMODE_WRITE) &&
> -	     atomic_read(&inode->i_writecount) == 1)) {
> +	     atomic_read(&inode->i_writecount) == 1)
> +	   /*
> +	    * The only file when inode->i_fop = &ntfs_file_operations and
> +	    * init_rwsem(&ni->file.run_lock) is not called explicitly is MFT.
> +	    *
> +	    * Add additional check here.
> +	    */
> +	    && inode->i_ino != MFT_REC_MFT) {
>  		ni_lock(ni);
>  		down_write(&ni->file.run_lock);
>