Re: [PATCH] coccinelle: Improve setup_timer.cocci matching

[Julia Lawall]

On Tue, 22 Aug 2017, Kees Cook wrote:

> This improves the patch mode of setup_timer.cocci. Several patterns were
> missing:
>  - assignments-before-init_timer() cases
>  - limiting the .data case removal to the struct timer_list instance
>  - handling calls by dereference (timer->field vs timer.field)
>
> Running this on the current kernel tree produces a large diff that I
> would like to get applied as the first step in removing the .data
> field from struct timer_list:
>
>  208 files changed, 367 insertions(+), 757 deletions(-)
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  scripts/coccinelle/api/setup_timer.cocci | 129 +++++++++++++++++++++++++------
>  1 file changed, 105 insertions(+), 24 deletions(-)
>
> diff --git a/scripts/coccinelle/api/setup_timer.cocci b/scripts/coccinelle/api/setup_timer.cocci
> index eb6bd9e4ab1a..bc6bd8f0b4bf 100644
> --- a/scripts/coccinelle/api/setup_timer.cocci
> +++ b/scripts/coccinelle/api/setup_timer.cocci
> @@ -2,6 +2,7 @@
>  /// and data fields
>  // Confidence: High
>  // Copyright: (C) 2016 Vaishali Thakkar, Oracle. GPLv2
> +// Copyright: (C) 2017 Kees Cook, Google. GPLv2
>  // Options: --no-includes --include-headers
>  // Keywords: init_timer, setup_timer
>
> @@ -10,60 +11,123 @@ virtual context
>  virtual org
>  virtual report
>
> +// Match the common cases first to avoid Coccinelle parsing loops with
> +// "... when" clauses.
> +
>  @match_immediate_function_data_after_init_timer
>  depends on patch && !context && !org && !report@
>  expression e, func, da;
>  @@
>
> --init_timer (&e);
> -+setup_timer (&e, func, da);
> +-init_timer
> ++setup_timer
> + ( \(&e\|e\)
> ++, func, da
> + );
> +(
> +-\(e.function\|e->function\) = func;
> +-\(e.data\|e->data\) = da;
> +|
> +-\(e.function\|e->function\) = func;
> +-\(e.data\|e->data\) = da;

Same thing twice; I think you want to invert the last two lines.

> +)
> +
> +@match_immediate_function_data_before_init_timer
> +depends on patch && !context && !org && !report@
> +expression e, func, da;
> +@@
>
>  (
> +-\(e.function\|e->function\) = func;
> +-\(e.data\|e->data\) = da;
> +|
> +-\(e.function\|e->function\) = func;
> +-\(e.data\|e->data\) = da;

Same as in the previous case.

julia


> +)
> +-init_timer
> ++setup_timer
> + ( \(&e\|e\)
> ++, func, da
> + );
> +
> +@match_function_and_data_after_init_timer
> +depends on patch && !context && !org && !report@
> +expression e, e2, e3, e4, e5, func, da;
> +@@
> +
> +-init_timer
> ++setup_timer
> + ( \(&e\|e\)
> ++, func, da
> + );
> + ... when != func = e2
> +     when != da = e3
> +(
>  -e.function = func;
> +... when != da = e4
>  -e.data = da;
>  |
> +-e->function = func;
> +... when != da = e4
> +-e->data = da;
> +|
>  -e.data = da;
> +... when != func = e5
>  -e.function = func;
> +|
> +-e->data = da;
> +... when != func = e5
> +-e->function = func;
>  )
>
> -@match_function_and_data_after_init_timer
> +@match_function_and_data_before_init_timer
>  depends on patch && !context && !org && !report@
> -expression e1, e2, e3, e4, e5, a, b;
> +expression e, e2, e3, e4, e5, func, da;
>  @@
> -
> --init_timer (&e1);
> -+setup_timer (&e1, a, b);
> -
> -... when != a = e2
> -    when != b = e3
>  (
> --e1.function = a;
> -... when != b = e4
> --e1.data = b;
> +-e.function = func;
> +... when != da = e4
> +-e.data = da;
>  |
> --e1.data = b;
> -... when != a = e5
> --e1.function = a;
> +-e->function = func;
> +... when != da = e4
> +-e->data = da;
> +|
> +-e.data = da;
> +... when != func = e5
> +-e.function = func;
> +|
> +-e->data = da;
> +... when != func = e5
> +-e->function = func;
>  )
> +... when != func = e2
> +    when != da = e3
> +-init_timer
> ++setup_timer
> + ( \(&e\|e\)
> ++, func, da
> + );
>
>  @r1 exists@
> +expression t;
>  identifier f;
>  position p;
>  @@
>
>  f(...) { ... when any
> -  init_timer@p(...)
> +  init_timer@p(\(&t\|t\))
>    ... when any
>  }
>
>  @r2 exists@
> +expression r1.t;
>  identifier g != r1.f;
> -struct timer_list t;
>  expression e8;
>  @@
>
>  g(...) { ... when any
> -  t.data = e8
> +  \(t.data\|t->data\) = e8
>    ... when any
>  }
>
> @@ -77,14 +141,31 @@ p << r1.p;
>  cocci.include_match(False)
>
>  @r3 depends on patch && !context && !org && !report@
> -expression e6, e7, c;
> +expression r1.t, func, e7;
>  position r1.p;
>  @@
>
> --init_timer@p (&e6);
> -+setup_timer (&e6, c, 0UL);
> -... when != c = e7
> --e6.function = c;
> +(
> +-init_timer@p(&t);
> ++setup_timer(&t, func, 0UL);
> +... when != func = e7
> +-t.function = func;
> +|
> +-t.function = func;
> +... when != func = e7
> +-init_timer@p(&t);
> ++setup_timer(&t, func, 0UL);
> +|
> +-init_timer@p(t);
> ++setup_timer(t, func, 0UL);
> +... when != func = e7
> +-t->function = func;
> +|
> +-t->function = func;
> +... when != func = e7
> +-init_timer@p(t);
> ++setup_timer(t, func, 0UL);
> +)
>
>  // ----------------------------------------------------------------------------
>
> --
> 2.7.4
>
>
> --
> Kees Cook
> Pixel Security
>