Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161636AbbKSUuO (ORCPT ); Thu, 19 Nov 2015 15:50:14 -0500 Received: from mail-ob0-f170.google.com ([209.85.214.170]:33835 "EHLO mail-ob0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934448AbbKSUuL (ORCPT ); Thu, 19 Nov 2015 15:50:11 -0500 MIME-Version: 1.0 In-Reply-To: <4295635.bqyeD1RN5z@avalon> References: <1447958344-836-1-git-send-email-geert+renesas@glider.be> <1447958344-836-10-git-send-email-geert+renesas@glider.be> <4295635.bqyeD1RN5z@avalon> Date: Thu, 19 Nov 2015 21:50:10 +0100 X-Google-Sender-Auth: Wr124CTznmUw6Vv2nWztEAPjmJU Message-ID: Subject: Re: [PATCH 09/25] serial: sh-sci: Avoid overflow in sci_baud_calc_hscif() From: Geert Uytterhoeven To: Laurent Pinchart Cc: Geert Uytterhoeven , Greg Kroah-Hartman , Simon Horman , Magnus Damm , Yoshinori Sato , "linux-serial@vger.kernel.org" , Linux-sh list , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1991 Lines: 48 On Thu, Nov 19, 2015 at 9:37 PM, Laurent Pinchart wrote: >> --- a/drivers/tty/serial/sh-sci.c >> +++ b/drivers/tty/serial/sh-sci.c >> @@ -1870,7 +1870,7 @@ static unsigned int sci_scbrr_calc(struct sci_port *s, >> unsigned int bps, static void sci_baud_calc_hscif(unsigned int bps, >> unsigned long freq, int *brr, unsigned int *srr, unsigned int *cks) >> { >> - unsigned int sr, br, c; >> + unsigned int sr, br, a, b, c; >> int err, recv_margin; >> int min_err = 1000; /* 100% */ >> int recv_max_margin = 0; >> @@ -1880,12 +1880,14 @@ static void sci_baud_calc_hscif(unsigned int bps, >> unsigned long freq, int *brr, for (sr = 8; sr <= 32; sr++) { >> for (c = 0; c <= 3; c++) { >> /* integerized formulas from HSCIF documentation */ >> - br = DIV_ROUND_CLOSEST(freq, (sr * >> - (1 << (2 * c + 1)) * bps)); >> + a = sr * (1 << (2 * c + 1)); >> + if (bps > UINT_MAX / a) >> + break; >> + >> + b = a * bps; > > This is becoming unreadable. Could you please use proper variable names ? A Sometimes it's different to find good variable names ("t1" and "t2"?). > comment that explains the calculation would also be useful. Thanks, that would indeed help. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/