linux-kernel - Re: [PATCH 1/3] auxdisplay: charlcd: fix hex literal ranges for graphics command

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]

Date:   Sat, 10 Feb 2018 09:58:44 +0100
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Willy Tarreau <w@....eu>, Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Robert Abel <rabel@...ertabel.eu>
Subject: Re: [PATCH 1/3] auxdisplay: charlcd: fix hex literal ranges for
 graphics command

On Sat, Feb 10, 2018 at 12:50 AM, Robert Abel <rabel@...ertabel.eu> wrote:
> The graphics command expects 16 hexadecimal literals, but would allow characters in range [0-9a-zA-Z] instead of [0-9a-fA-F].
>
> Signed-off-by: Robert Abel <rabel@...ertabel.eu>
> ---
>  drivers/auxdisplay/charlcd.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
> index 642afd88870b..324d02f9f1c5 100644
> --- a/drivers/auxdisplay/charlcd.c
> +++ b/drivers/auxdisplay/charlcd.c
> @@ -441,9 +441,9 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
>                         shift ^= 4;
>                         if (*esc >= '0' && *esc <= '9') {
>                                 value |= (*esc - '0') << shift;
> -                       } else if (*esc >= 'A' && *esc <= 'Z') {
> +                       } else if (*esc >= 'A' && *esc <= 'F') {
>                                 value |= (*esc - 'A' + 10) << shift;
> -                       } else if (*esc >= 'a' && *esc <= 'z') {
> +                       } else if (*esc >= 'a' && *esc <= 'f') {

Willy, Geert: this seems obvious, but do you know if the broader range
was intended for some reason? In that case, adding a comment to the
code would be good. I found some related docs at
Documentation/misc-devices/lcd-panel-cgram.txt by Willy (which, by the
way, maybe now we should move them to Documentations/auxdisplay); but
the paragraph does indeed say they have to be hex:

'''
Some LCDs allow you to define up to 8 characters, mapped to ASCII
characters 0 to 7. The escape code to define a new character is
'\e[LG' followed by one digit from 0 to 7, representing the character
number, and up to 8 couples of hex digits terminated by a semi-colon
(';').
'''

>                                 value |= (*esc - 'a' + 10) << shift;
>                         } else {
>                                 esc++;
> --
> 2.11.0
>