1// SPDX-License-Identifier: GPL-2.0-only
2/// Find a use after free.
3//# Values of variables may imply that some
4//# execution paths are not possible, resulting in false positives.
5//# Another source of false positives are macros such as
6//# SCTP_DBG_OBJCNT_DEC that do not actually evaluate their argument
7///
8// Confidence: Moderate
9// Copyright: (C) 2010-2012 Nicolas Palix.
10// Copyright: (C) 2010-2012 Julia Lawall, INRIA/LIP6.
11// Copyright: (C) 2010-2012 Gilles Muller, INRIA/LiP6.
12// URL: http://coccinelle.lip6.fr/
13// Comments:
14// Options: --no-includes --include-headers
15
16virtual org
17virtual report
18
19@free@
20expression E;
21position p1;
22@@
23
24(
25* kfree@p1(E)
26|
27* kfree_sensitive@p1(E)
28)
29
30@print expression@
31constant char [] c;
32expression free.E,E2;
33type T;
34position p;
35identifier f;
36@@
37
38(
39 f(...,c,...,(T)E@p,...)
40|
41 E@p == E2
42|
43 E@p != E2
44|
45 E2 == E@p
46|
47 E2 != E@p
48|
49 !E@p
50|
51 E@p || ...
52)
53
54@sz@
55expression free.E;
56position p;
57@@
58
59 sizeof(<+...E@p...+>)
60
61@loop exists@
62expression E;
63identifier l;
64position ok;
65@@
66
67while (1) { ...
68(
69* kfree@ok(E)
70|
71* kfree_sensitive@ok(E)
72)
73  ... when != break;
74      when != goto l;
75      when forall
76}
77
78@r exists@
79expression free.E, subE<=free.E, E2;
80expression E1;
81iterator iter;
82statement S;
83position free.p1!=loop.ok,p2!={print.p,sz.p};
84@@
85
86(
87* kfree@p1(E,...)
88|
89* kfree_sensitive@p1(E,...)
90)
91...
92(
93 iter(...,subE,...) S // no use
94|
95 list_remove_head(E1,subE,...)
96|
97 subE = E2
98|
99 subE++
100|
101 ++subE
102|
103 --subE
104|
105 subE--
106|
107 &subE
108|
109 BUG(...)
110|
111 BUG_ON(...)
112|
113 return_VALUE(...)
114|
115 return_ACPI_STATUS(...)
116|
117 E@p2 // bad use
118)
119
120@script:python depends on org@
121p1 << free.p1;
122p2 << r.p2;
123@@
124
125cocci.print_main("kfree",p1)
126cocci.print_secs("ref",p2)
127
128@script:python depends on report@
129p1 << free.p1;
130p2 << r.p2;
131@@
132
133msg = "ERROR: reference preceded by free on line %s" % (p1[0].line)
134coccilib.report.print_report(p2[0],msg)
135