linux-kernel - Re: [PATCH] scripts: kzfree.cocci: Deprecate use of kzfree

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Date:   Fri, 11 Sep 2020 17:19:53 +0100
From:   Alex Dewar <alex.dewar90@...il.com>
To:     efremov@...ux.com, Julia Lawall <Julia.Lawall@...6.fr>
Cc:     Gilles Muller <Gilles.Muller@...6.fr>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Michal Marek <michal.lkml@...kovi.net>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jonathan Corbet <corbet@....net>, cocci@...teme.lip6.fr,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scripts: kzfree.cocci: Deprecate use of kzfree

On 2020-09-11 17:08, Denis Efremov wrote:
> Hi,
>
> same patch
> https://lkml.org/lkml/2020/8/11/130
>
> Julia, I've send all the patches to fix existing kfree_sensitive/kvfree_sensitive reports.
>
> https://lkml.org/lkml/2020/8/27/168
> https://lkml.org/lkml/2020/8/27/93
>
> Thanks,
> Denis
Sorry for yet more noise!
>
> On 9/11/20 4:49 PM, Alex Dewar wrote:
>> kzfree() is effectively deprecated as of commit 453431a54934 ("mm,
>> treewide: rename kzfree() to kfree_sensitive()"). It is currently just a
>> legacy alias for kfree_sensitive(), which achieves the same thing.
>>
>> Update kzfree.cocci accordingly:
>> 1) Replace instances of kzfree with kfree_sensitive
>> 2) Merge different rules for memset/memset_explicit as kzfree and
>>     kfree_sensitive are now equivalent
>> 3) Rename script to kfree_sensitive.cocci
>>
>> In addition:
>> 4) Move the script to the free/ subfolder, where it would seem to fit
>>     better
>>
>> Signed-off-by: Alex Dewar <alex.dewar90@...il.com>
>> ---
>>   .../kfree_sensitive.cocci}                    | 38 +++++--------------
>>   1 file changed, 10 insertions(+), 28 deletions(-)
>>   rename scripts/coccinelle/{api/kzfree.cocci => free/kfree_sensitive.cocci} (59%)
>>
>> diff --git a/scripts/coccinelle/api/kzfree.cocci b/scripts/coccinelle/free/kfree_sensitive.cocci
>> similarity index 59%
>> rename from scripts/coccinelle/api/kzfree.cocci
>> rename to scripts/coccinelle/free/kfree_sensitive.cocci
>> index 33625bd7cec9..a87f93f2ed5c 100644
>> --- a/scripts/coccinelle/api/kzfree.cocci
>> +++ b/scripts/coccinelle/free/kfree_sensitive.cocci
>> @@ -1,13 +1,13 @@
>>   // SPDX-License-Identifier: GPL-2.0-only
>>   ///
>> -/// Use kzfree, kvfree_sensitive rather than memset or
>> -/// memzero_explicit followed by kfree
>> +/// Use k{,v}free_sensitive rather than memset or memzero_explicit followed by
>> +/// k{,v}free
>>   ///
>>   // Confidence: High
>>   // Copyright: (C) 2020 Denis Efremov ISPRAS
>>   // Options: --no-includes --include-headers
>>   //
>> -// Keywords: kzfree, kvfree_sensitive
>> +// Keywords: kfree_sensitive, kvfree_sensitive
>>   //
>>   
>>   virtual context
>> @@ -18,7 +18,7 @@ virtual report
>>   @initialize:python@
>>   @@
>>   # kmalloc_oob_in_memset uses memset to explicitly trigger out-of-bounds access
>> -filter = frozenset(['kmalloc_oob_in_memset', 'kzfree', 'kvfree_sensitive'])
>> +filter = frozenset(['kmalloc_oob_in_memset', 'kfree_sensitive', 'kvfree_sensitive'])
>>   
>>   def relevant(p):
>>       return not (filter & {el.current_element for el in p})
>> @@ -53,34 +53,16 @@ position m != cond.ok;
>>   type T;
>>   @@
>>   
>> +(
>>   - memzero_explicit@m((T)E, size);
>> -  ... when != E
>> -      when strict
>> -// TODO: uncomment when kfree_sensitive will be merged.
>> -// Only this case is commented out because developers
>> -// may not like patches like this since kzfree uses memset
>> -// internally (not memzero_explicit).
>> -//(
>> -//- kfree(E)@p;
>> -//+ kfree_sensitive(E);
>> -//|
>> -- \(vfree\|kvfree\)(E)@p;
>> -+ kvfree_sensitive(E, size);
>> -//)
>> -
>> -@...memset depends on patch@
>> -expression E, size;
>> -position p : script:python() { relevant(p) };
>> -position m != cond.ok;
>> -type T;
>> -@@
>> -
>> +|
>>   - memset@m((T)E, 0, size);
>> +)
>>     ... when != E
>>         when strict
>>   (
>>   - kfree(E)@p;
>> -+ kzfree(E);
>> ++ kfree_sensitive(E);
>>   |
>>   - \(vfree\|kvfree\)(E)@p;
>>   + kvfree_sensitive(E, size);
>> @@ -91,11 +73,11 @@ p << r.p;
>>   @@
>>   
>>   coccilib.report.print_report(p[0],
>> -  "WARNING: opportunity for kzfree/kvfree_sensitive")
>> +  "WARNING: opportunity for k{,v}free_sensitive")
>>   
>>   @script:python depends on org@
>>   p << r.p;
>>   @@
>>   
>>   coccilib.org.print_todo(p[0],
>> -  "WARNING: opportunity for kzfree/kvfree_sensitive")
>> +  "WARNING: opportunity for k{,v}free_sensitive")
>>