Re: [PATCH] x86/uaccess: small optimization in unsafe_copy_to_user()

[Al Viro]

On Sat, Apr 17, 2021 at 08:30:42PM +0000, Al Viro wrote:

> and that thing is still there.  However, it does *NOT* do what it might
> appear to be doing; it ends up with getdents() returning -EINVAL instead.
> What we need is
> 			buf->error = -EINTR;
> in addition to that return (in all 3 such places).  Do you have any problems with
> the following delta?

No, wait - we have non-NULL buf->prev_reclen, so we'll hit
        if (buf.prev_reclen) {
		struct compat_linux_dirent __user * lastdirent;
		lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;

		if (put_user(buf.ctx.pos, &lastdirent->d_off)) 
			error = -EFAULT;
		else
			error = count - buf.count;
	}
with buf->error completely ignored.  Nevermind.