linux-kernel - Re: [PATCH] Convert filldir[64]() from __put_user() to unsafe_put

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Message-ID: <20191008152900.GT26530@ZenIV.linux.org.uk>
Date:   Tue, 8 Oct 2019 16:29:00 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] Convert filldir[64]() from __put_user() to
 unsafe_put_user()

On Tue, Oct 08, 2019 at 03:14:16PM +0200, Greg KH wrote:
> On Tue, Oct 08, 2019 at 05:57:12AM +0100, Al Viro wrote:
> > 
> > 	OK...  BTW, do you agree that the use of access_ok() in
> > drivers/tty/n_hdlc.c:n_hdlc_tty_read() is wrong?  It's used as an early
> > cutoff, so we don't bother waiting if user has passed an obviously bogus
> > address.  copy_to_user() is used for actual copying there...
> 
> Yes, it's wrong, and not needed.  I'll go rip it out unless you want to?

I'll throw it into misc queue for now; it has no prereqs and nothing is going
to depend upon it.

While looking for more of the same pattern: usb_device_read().  Frankly,
usb_device_dump() calling conventions look ugly - it smells like it
would be much happier as seq_file.  Iterator would take some massage,
but that seems to be doable.  Anyway, that's a separate story...