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

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Date:   Fri, 11 Sep 2020 19:08:37 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Alex Dewar <alex.dewar90@...il.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

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

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")
>