linux-kernel - Re: [PATCH v1 1/2] tty/vt: Use KVAL instead of use bit operation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z7WjABCTLE4CisKY@example.org>
Date: Wed, 19 Feb 2025 10:23:12 +0100
From: Alexey Gladkov <legion@...nel.org>
To: Jiri Slaby <jirislaby@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-serial@...r.kernel.org
Subject: Re: [PATCH v1 1/2] tty/vt: Use KVAL instead of use bit operation

On Wed, Feb 19, 2025 at 07:24:52AM +0100, Jiri Slaby wrote:
> On 18. 02. 25, 13:29, Alexey Gladkov wrote:
> > The K_HANDLERS always gets KVAL as an argument. It is better to use the
> > KVAL macro itself instead of bit operation.
> > 
> > Signed-off-by: Alexey Gladkov <legion@...nel.org>
> > ---
> >   drivers/tty/vt/keyboard.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> > index 804355da46f5..7df041ac4d5c 100644
> > --- a/drivers/tty/vt/keyboard.c
> > +++ b/drivers/tty/vt/keyboard.c
> > @@ -885,7 +885,7 @@ static void k_shift(struct vc_data *vc, unsigned char value, char up_flag)
> >   		if (kbd->kbdmode == VC_UNICODE)
> >   			to_utf8(vc, npadch_value);
> >   		else
> > -			put_queue(vc, npadch_value & 0xff);
> > +			put_queue(vc, KVAL(npadch_value));
> 
> While the mask is the same, this is not a kval, right?

I'm pretty sure it's KVAL, but to be honest I don't understand why it is
not done for to_utf8() as well. All values passed to to_utf8() must be
kval.

We call to_utf8() in k_unicode, fn_enter (through k_spec), handle_diacr
(through k_deadunicode or k_unicode). All K_HANDLERS take KVAL as value.

If I understand this code correctly, it is more correct to write it like
this:

--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -882,10 +882,11 @@ static void k_shift(struct vc_data *vc, unsigned char value, char up_flag)

        /* kludge */
        if (up_flag && shift_state != old_state && npadch_active) {
+               u32 kval = KVAL(npadch_value);
                if (kbd->kbdmode == VC_UNICODE)
-                       to_utf8(vc, npadch_value);
+                       to_utf8(vc, kval);
                else
-                       put_queue(vc, npadch_value & 0xff);
+                       put_queue(vc, kval);
                npadch_active = false;
        }
 }

But I may be wrong because the code about npadch_value is very old and I
may be missing something.

> >   		npadch_active = false;
> >   	}
> >   }
> > @@ -1519,7 +1519,7 @@ static void kbd_keycode(unsigned int keycode, int down, bool hw_raw)
> >   	if ((raw_mode || kbd->kbdmode == VC_OFF) && type != KT_SPEC && type != KT_SHIFT)
> >   		return;
> >   
> > -	(*k_handler[type])(vc, keysym & 0xff, !down);
> > +	(*k_handler[type])(vc, KVAL(keysym), !down);
> 
> This makes sense.
> 
> -- 
> js
> suse labs
> 

-- 
Rgrds, legion