Coccinelle: Script to detect incorrect argument to sizeof

This makes an effort to find cases where the argument to sizeof is wrong
in memory allocation functions by checking the type of the allocated
memory when it is a double pointer and ensuring the sizeof argument takes
a pointer to the the memory being allocated. There are false positives
in cases the sizeof argument is not used in constructing the return value.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/misc/badty.cocci

@@ -0,0 +1,76 @@
+/// Use ARRAY_SIZE instead of dividing sizeof array with sizeof an element
+///
+//# This makes an effort to find cases where the argument to sizeof is wrong
+//# in memory allocation functions by checking the type of the allocated memory
+//# when it is a double pointer and ensuring the sizeof argument takes a pointer
+//# to the the memory being allocated. There are false positives in cases the
+//# sizeof argument is not used in constructing the return value. The result
+//# may need some reformatting.
+//
+// Confidence: Moderate
+// Copyright: (C) 2014 Himangi Saraogi.  GPLv2.
+// Comments:
+// Options:
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+//----------------------------------------------------------
+//  For context mode
+//----------------------------------------------------------
+
+@depends on context disable sizeof_type_expr@
+type T;
+T **x;
+@@
+
+  x =
+  <+...sizeof(
+* T
+  )...+>
+
+//----------------------------------------------------------
+//  For patch mode
+//----------------------------------------------------------
+
+@depends on patch disable sizeof_type_expr@
+type T;
+T **x;
+@@
+
+  x =
+  <+...sizeof(
+- T
++ *x
+  )...+>
+
+//----------------------------------------------------------
+//  For org and report mode
+//----------------------------------------------------------
+
+@r disable sizeof_type_expr@
+type T;
+T **x;
+position p;
+@@
+
+  x =
+  <+...sizeof(
+  T@p
+  )...+>
+
+@script:python depends on org@
+p << r.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING sizeof argument should be pointer type, not structure type")
+
+@script:python depends on report@
+p << r.p;
+@@
+
+msg="WARNING: Use correct pointer type argument for sizeof"
+coccilib.report.print_report(p[0], msg)
+