Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753791AbbGPGkf (ORCPT ); Thu, 16 Jul 2015 02:40:35 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:35707 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753702AbbGPGkc (ORCPT ); Thu, 16 Jul 2015 02:40:32 -0400 MIME-Version: 1.0 In-Reply-To: <1437023722-7432-1-git-send-email-ysato@users.sourceforge.jp> References: <1437023722-7432-1-git-send-email-ysato@users.sourceforge.jp> Date: Thu, 16 Jul 2015 08:40:31 +0200 X-Google-Sender-Auth: 7RmwvrtCkaZ2bQP8VMiaYS7zcSE Message-ID: Subject: Re: [PATCH] asm-generic: {get,put}_user ptr argument evaluate only 1 time From: Geert Uytterhoeven To: Yoshinori Sato Cc: Arnd Bergmann , Linux-Arch , "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: 2596 Lines: 63 Hi Sato-san, On Thu, Jul 16, 2015 at 7:15 AM, Yoshinori Sato wrote: > Current implemantation ptr argument evaluate 2 times. > It'll be an unexpected result. > > Signed-off-by: Yoshinori Sato Acked-by: Geert Uytterhoeven > --- > include/asm-generic/uaccess.h | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h > index 72d8803..1b813fb 100644 > --- a/include/asm-generic/uaccess.h > +++ b/include/asm-generic/uaccess.h > @@ -163,9 +163,10 @@ static inline __must_check long __copy_to_user(void __user *to, > > #define put_user(x, ptr) \ > ({ \ > + __typeof__((ptr)) __p = (ptr); \ > might_fault(); \ > - access_ok(VERIFY_WRITE, ptr, sizeof(*ptr)) ? \ > - __put_user(x, ptr) : \ > + access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ > + __put_user(x, __p) : \ For safety, you may want to change "x" to "(x") while at it. > -EFAULT; \ > }) > > @@ -225,9 +226,10 @@ extern int __put_user_bad(void) __attribute__((noreturn)); > > #define get_user(x, ptr) \ > ({ \ > + __typeof__((ptr)) __p = (ptr); \ > might_fault(); \ > - access_ok(VERIFY_READ, ptr, sizeof(*ptr)) ? \ > - __get_user(x, ptr) : \ > + access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ > + __get_user(x, __p) : \ Likewise. 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/