From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 707CAC33CA4 for ; Sat, 11 Jan 2020 15:36:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50FDB20842 for ; Sat, 11 Jan 2020 15:36:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730043AbgAKPgc (ORCPT ); Sat, 11 Jan 2020 10:36:32 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:23863 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729989AbgAKPgc (ORCPT ); Sat, 11 Jan 2020 10:36:32 -0500 X-IronPort-AV: E=Sophos;i="5.69,421,1571695200"; d="scan'208";a="430910632" Received: from abo-154-110-68.mrs.modulonet.fr (HELO hadrien) ([85.68.110.154]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jan 2020 16:36:29 +0100 Date: Sat, 11 Jan 2020 16:36:28 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Wen Yang cc: Gilles Muller , Nicolas Palix , Michal Marek , Matthias Maennich , Greg Kroah-Hartman , Masahiro Yamada , Thomas Gleixner , cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] coccinelle: semantic patch to check for inappropriate do_div() calls In-Reply-To: <20200110131526.60180-1-wenyang@linux.alibaba.com> Message-ID: References: <20200110131526.60180-1-wenyang@linux.alibaba.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 10 Jan 2020, Wen Yang wrote: > do_div() does a 64-by-32 division. > When the divisor is unsigned long, u64, or s64, > do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. > This semantic patch is inspired by Mateusz Guzik's patch: > commit b0ab99e7736a ("sched: Fix possible divide by zero in avg_atom() calculation") > > Signed-off-by: Wen Yang Acked-by: Julia Lawall This looks good to me. A small detail is that you don't need the parentheses in: @r depends on (org || report)@ julia > Cc: Julia Lawall > Cc: Gilles Muller > Cc: Nicolas Palix > Cc: Michal Marek > Cc: Matthias Maennich > Cc: Greg Kroah-Hartman > Cc: Masahiro Yamada > Cc: Thomas Gleixner > Cc: cocci@systeme.lip6.fr > Cc: linux-kernel@vger.kernel.org > --- > v3: > - also filter out safe consts for context mode. > - cleanup code. > > v2: > - add a special case for constants and checking whether the value is obviously safe and no warning is needed. > - fix 'WARNING:' twice in each case. > - extend the warning to say "consider using div64_xxx instead". > > scripts/coccinelle/misc/do_div.cocci | 155 +++++++++++++++++++++++++++ > 1 file changed, 155 insertions(+) > create mode 100644 scripts/coccinelle/misc/do_div.cocci > > diff --git a/scripts/coccinelle/misc/do_div.cocci b/scripts/coccinelle/misc/do_div.cocci > new file mode 100644 > index 000000000000..79db083c5208 > --- /dev/null > +++ b/scripts/coccinelle/misc/do_div.cocci > @@ -0,0 +1,155 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/// do_div() does a 64-by-32 division. > +/// When the divisor is long, unsigned long, u64, or s64, > +/// do_div() truncates it to 32 bits, this means it can test > +/// non-zero and be truncated to 0 for division on 64bit platforms. > +/// > +//# This makes an effort to find those inappropriate do_div() calls. > +// > +// Confidence: Moderate > +// Copyright: (C) 2020 Wen Yang, Alibaba. > +// Comments: > +// Options: --no-includes --include-headers > + > +virtual context > +virtual org > +virtual report > + > +@initialize:python@ > +@@ > + > +def get_digit_type_and_value(str): > + is_digit = False > + value = 0 > + > + try: > + if (str.isdigit()): > + is_digit = True > + value = int(str, 0) > + elif (str.upper().endswith('ULL')): > + is_digit = True > + value = int(str[:-3], 0) > + elif (str.upper().endswith('LL')): > + is_digit = True > + value = int(str[:-2], 0) > + elif (str.upper().endswith('UL')): > + is_digit = True > + value = int(str[:-2], 0) > + elif (str.upper().endswith('L')): > + is_digit = True > + value = int(str[:-1], 0) > + elif (str.upper().endswith('U')): > + is_digit = True > + value = int(str[:-1], 0) > + except Exception as e: > + print('Error:',e) > + is_digit = False > + value = 0 > + finally: > + return is_digit, value > + > +def filter_out_safe_constants(str): > + is_digit, value = get_digit_type_and_value(str) > + if (is_digit): > + if (value >= 0x100000000): > + return True > + else: > + return False > + else: > + return True > + > +def construct_warnings(suggested_fun): > + msg="WARNING: do_div() does a 64-by-32 division, please consider using %s instead." > + return msg % suggested_fun > + > +@depends on context@ > +expression f; > +long l: script:python() { filter_out_safe_constants(l) }; > +unsigned long ul : script:python() { filter_out_safe_constants(ul) }; > +u64 ul64 : script:python() { filter_out_safe_constants(ul64) }; > +s64 sl64 : script:python() { filter_out_safe_constants(sl64) }; > + > +@@ > +( > +* do_div(f, l); > +| > +* do_div(f, ul); > +| > +* do_div(f, ul64); > +| > +* do_div(f, sl64); > +) > + > +@r depends on (org || report)@ > +expression f; > +position p; > +long l: script:python() { filter_out_safe_constants(l) }; > +unsigned long ul : script:python() { filter_out_safe_constants(ul) }; > +u64 ul64 : script:python() { filter_out_safe_constants(ul64) }; > +s64 sl64 : script:python() { filter_out_safe_constants(sl64) }; > +@@ > +( > +do_div@p(f, l); > +| > +do_div@p(f, ul); > +| > +do_div@p(f, ul64); > +| > +do_div@p(f, sl64); > +) > + > +@script:python depends on org@ > +p << r.p; > +ul << r.ul; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_ul")) > + > +@script:python depends on org@ > +p << r.p; > +l << r.l; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_long")) > + > +@script:python depends on org@ > +p << r.p; > +ul64 << r.ul64; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_u64")) > + > +@script:python depends on org@ > +p << r.p; > +sl64 << r.sl64; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_s64")) > + > +@script:python depends on report@ > +p << r.p; > +ul << r.ul; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_ul")) > + > +@script:python depends on report@ > +p << r.p; > +l << r.l; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_long")) > + > +@script:python depends on report@ > +p << r.p; > +sl64 << r.sl64; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_s64")) > + > +@script:python depends on report@ > +p << r.p; > +ul64 << r.ul64; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_u64")) > -- > 2.23.0 > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C1ADC282DD for ; 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Sat, 11 Jan 2020 16:36:30 +0100 (CET) Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by isis.lip6.fr (8.15.2/8.15.2) with ESMTP id 00BFaTcF007785 for ; Sat, 11 Jan 2020 16:36:29 +0100 (CET) X-IronPort-AV: E=Sophos;i="5.69,421,1571695200"; d="scan'208";a="430910632" Received: from abo-154-110-68.mrs.modulonet.fr (HELO hadrien) ([85.68.110.154]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jan 2020 16:36:29 +0100 Date: Sat, 11 Jan 2020 16:36:28 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Wen Yang In-Reply-To: <20200110131526.60180-1-wenyang@linux.alibaba.com> Message-ID: References: <20200110131526.60180-1-wenyang@linux.alibaba.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Greylist: Sender IP whitelisted, Sender e-mail whitelisted, not delayed by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Sat, 11 Jan 2020 16:36:33 +0100 (CET) X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.4.3 (isis.lip6.fr [132.227.60.2]); Sat, 11 Jan 2020 16:36:29 +0100 (CET) X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 X-Scanned-By: MIMEDefang 2.78 on 132.227.60.2 Cc: Michal Marek , Gilles Muller , Nicolas Palix , Matthias Maennich , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Thomas Gleixner , cocci@systeme.lip6.fr Subject: Re: [Cocci] [PATCH v3] coccinelle: semantic patch to check for inappropriate do_div() calls X-BeenThere: cocci@systeme.lip6.fr X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: cocci-bounces@systeme.lip6.fr Errors-To: cocci-bounces@systeme.lip6.fr On Fri, 10 Jan 2020, Wen Yang wrote: > do_div() does a 64-by-32 division. > When the divisor is unsigned long, u64, or s64, > do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. > This semantic patch is inspired by Mateusz Guzik's patch: > commit b0ab99e7736a ("sched: Fix possible divide by zero in avg_atom() calculation") > > Signed-off-by: Wen Yang Acked-by: Julia Lawall This looks good to me. A small detail is that you don't need the parentheses in: @r depends on (org || report)@ julia > Cc: Julia Lawall > Cc: Gilles Muller > Cc: Nicolas Palix > Cc: Michal Marek > Cc: Matthias Maennich > Cc: Greg Kroah-Hartman > Cc: Masahiro Yamada > Cc: Thomas Gleixner > Cc: cocci@systeme.lip6.fr > Cc: linux-kernel@vger.kernel.org > --- > v3: > - also filter out safe consts for context mode. > - cleanup code. > > v2: > - add a special case for constants and checking whether the value is obviously safe and no warning is needed. > - fix 'WARNING:' twice in each case. > - extend the warning to say "consider using div64_xxx instead". > > scripts/coccinelle/misc/do_div.cocci | 155 +++++++++++++++++++++++++++ > 1 file changed, 155 insertions(+) > create mode 100644 scripts/coccinelle/misc/do_div.cocci > > diff --git a/scripts/coccinelle/misc/do_div.cocci b/scripts/coccinelle/misc/do_div.cocci > new file mode 100644 > index 000000000000..79db083c5208 > --- /dev/null > +++ b/scripts/coccinelle/misc/do_div.cocci > @@ -0,0 +1,155 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/// do_div() does a 64-by-32 division. > +/// When the divisor is long, unsigned long, u64, or s64, > +/// do_div() truncates it to 32 bits, this means it can test > +/// non-zero and be truncated to 0 for division on 64bit platforms. > +/// > +//# This makes an effort to find those inappropriate do_div() calls. > +// > +// Confidence: Moderate > +// Copyright: (C) 2020 Wen Yang, Alibaba. > +// Comments: > +// Options: --no-includes --include-headers > + > +virtual context > +virtual org > +virtual report > + > +@initialize:python@ > +@@ > + > +def get_digit_type_and_value(str): > + is_digit = False > + value = 0 > + > + try: > + if (str.isdigit()): > + is_digit = True > + value = int(str, 0) > + elif (str.upper().endswith('ULL')): > + is_digit = True > + value = int(str[:-3], 0) > + elif (str.upper().endswith('LL')): > + is_digit = True > + value = int(str[:-2], 0) > + elif (str.upper().endswith('UL')): > + is_digit = True > + value = int(str[:-2], 0) > + elif (str.upper().endswith('L')): > + is_digit = True > + value = int(str[:-1], 0) > + elif (str.upper().endswith('U')): > + is_digit = True > + value = int(str[:-1], 0) > + except Exception as e: > + print('Error:',e) > + is_digit = False > + value = 0 > + finally: > + return is_digit, value > + > +def filter_out_safe_constants(str): > + is_digit, value = get_digit_type_and_value(str) > + if (is_digit): > + if (value >= 0x100000000): > + return True > + else: > + return False > + else: > + return True > + > +def construct_warnings(suggested_fun): > + msg="WARNING: do_div() does a 64-by-32 division, please consider using %s instead." > + return msg % suggested_fun > + > +@depends on context@ > +expression f; > +long l: script:python() { filter_out_safe_constants(l) }; > +unsigned long ul : script:python() { filter_out_safe_constants(ul) }; > +u64 ul64 : script:python() { filter_out_safe_constants(ul64) }; > +s64 sl64 : script:python() { filter_out_safe_constants(sl64) }; > + > +@@ > +( > +* do_div(f, l); > +| > +* do_div(f, ul); > +| > +* do_div(f, ul64); > +| > +* do_div(f, sl64); > +) > + > +@r depends on (org || report)@ > +expression f; > +position p; > +long l: script:python() { filter_out_safe_constants(l) }; > +unsigned long ul : script:python() { filter_out_safe_constants(ul) }; > +u64 ul64 : script:python() { filter_out_safe_constants(ul64) }; > +s64 sl64 : script:python() { filter_out_safe_constants(sl64) }; > +@@ > +( > +do_div@p(f, l); > +| > +do_div@p(f, ul); > +| > +do_div@p(f, ul64); > +| > +do_div@p(f, sl64); > +) > + > +@script:python depends on org@ > +p << r.p; > +ul << r.ul; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_ul")) > + > +@script:python depends on org@ > +p << r.p; > +l << r.l; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_long")) > + > +@script:python depends on org@ > +p << r.p; > +ul64 << r.ul64; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_u64")) > + > +@script:python depends on org@ > +p << r.p; > +sl64 << r.sl64; > +@@ > + > +coccilib.org.print_todo(p[0], construct_warnings("div64_s64")) > + > +@script:python depends on report@ > +p << r.p; > +ul << r.ul; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_ul")) > + > +@script:python depends on report@ > +p << r.p; > +l << r.l; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_long")) > + > +@script:python depends on report@ > +p << r.p; > +sl64 << r.sl64; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_s64")) > + > +@script:python depends on report@ > +p << r.p; > +ul64 << r.ul64; > +@@ > + > +coccilib.report.print_report(p[0], construct_warnings("div64_u64")) > -- > 2.23.0 > > _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci