scripts/coccinelle/free/kfree.cocci

   1 /// Find a use after free.
   2 //# Values of variables may imply that some
   3 //# execution paths are not possible, resulting in false positives.
   4 //# Another source of false positives are macros such as
   5 //# SCTP_DBG_OBJCNT_DEC that do not actually evaluate their argument
   6 ///
   7 // Confidence: Moderate
   8 // Copyright: (C) 2010-2012 Nicolas Palix.  GPLv2.
   9 // Copyright: (C) 2010-2012 Julia Lawall, INRIA/LIP6.  GPLv2.
  10 // Copyright: (C) 2010-2012 Gilles Muller, INRIA/LiP6.  GPLv2.
  11 // URL: http://coccinelle.lip6.fr/
  12 // Comments:
  13 // Options: -no_includes -include_headers
  14
  15 virtual org
  16 virtual report
  17
  18 @free@
  19 expression E;
  20 position p1;
  21 @@
  22
  23 kfree@p1(E)
  24
  25 @print expression@
  26 constant char [] c;
  27 expression free.E,E2;
  28 type T;
  29 position p;
  30 identifier f;
  31 @@
  32
  33 (
  34  f(...,c,...,(T)E@p,...)
  35 |
  36  E@p == E2
  37 |
  38  E@p != E2
  39 |
  40  E2 == E@p
  41 |
  42  E2 != E@p
  43 |
  44  !E@p
  45 |
  46  E@p || ...
  47 )
  48
  49 @sz@
  50 expression free.E;
  51 position p;
  52 @@
  53
  54  sizeof(<+...E@p...+>)
  55
  56 @loop exists@
  57 expression E;
  58 identifier l;
  59 position ok;
  60 @@
  61
  62 while (1) { ...
  63   kfree@ok(E)
  64   ... when != break;
  65       when != goto l;
  66       when forall
  67 }
  68
  69 @r exists@
  70 expression free.E, subE<=free.E, E2;
  71 expression E1;
  72 iterator iter;
  73 statement S;
  74 position free.p1!=loop.ok,p2!={print.p,sz.p};
  75 @@
  76
  77 kfree@p1(E,...)
  78 ...
  79 (
  80  iter(...,subE,...) S // no use
  81 |
  82  list_remove_head(E1,subE,...)
  83 |
  84  subE = E2
  85 |
  86  subE++
  87 |
  88  ++subE
  89 |
  90  --subE
  91 |
  92  subE--
  93 |
  94  &subE
  95 |
  96  BUG(...)
  97 |
  98  BUG_ON(...)
  99 |
 100  return_VALUE(...)
 101 |
 102  return_ACPI_STATUS(...)
 103 |
 104  E@p2 // bad use
 105 )
 106
 107 @script:python depends on org@
 108 p1 << free.p1;
 109 p2 << r.p2;
 110 @@
 111
 112 cocci.print_main("kfree",p1)
 113 cocci.print_secs("ref",p2)
 114
 115 @script:python depends on report@
 116 p1 << free.p1;
 117 p2 << r.p2;
 118 @@
 119
 120 msg = "ERROR: reference preceded by free on line %s" % (p1[0].line)
 121 coccilib.report.print_report(p2[0],msg)