[dm-devel] [PATCH 0/8] replace memset by memzero_explicit

Julia Lawall Julia.Lawall at lip6.fr
Sun Nov 30 17:03:41 UTC 2014


Memset on a local variable may be removed when it is called just before the
variable goes out of scope.  Using memzero_explicit defeats this
optimization.  The complete semantic patch that makes this change is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier x;
local idexpression e;
type T,T1;
@@

{
... when any
T x[...];
... when any
    when exists
(
e = (T1)x
|
e = (T1)&x[0]
)
... when any
    when exists
- memset
+ memzero_explicit
  (x,
-0,
  ...)
... when != x
    when != e
    when strict
}

@@
identifier i,x;
local idexpression e;
type T;
@@

{
... when any
struct i x;
... when any
    when exists
e = (T)&x
... when any
    when exists
- memset
+ memzero_explicit
  (&x,
-0,
  ...)
... when != x
    when != e
    when strict
}

// ------------------------------------------------------------------------

@@
identifier x;
type T,T1;
expression e;
@@

{
... when any
T x[...];
... when any
    when exists
    when != e = (T1)x
    when != e = (T1)&x[0]
- memset
+ memzero_explicit
  (x,
-0,
  ...)
... when != x
    when strict
}

@@
identifier i,x;
expression e;
type T;
@@

{
... when any
struct i x;
... when any
    when exists
    when != e = (T)&x
- memset
+ memzero_explicit
  (&x,
-0,
  ...)
... when != x
    when strict
}
// </smpl>




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