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authorDenis Efremov <efremov@linux.com>2020-07-17 14:57:09 +0300
committerJulia Lawall <Julia.Lawall@lip6.fr>2020-08-04 22:46:59 +0200
commit7cf4be68b177855b620dbc045bf26606eed197ac (patch)
tree363bac4d98757b993a5b87ddab0b639aede08b73 /scripts/coccinelle
parentde50862520480b90ec2fcaed6ad1ad41462fbf30 (diff)
coccinelle: api: add kzfree script
Check for memset()/memzero_explicit() followed by kfree()/vfree()/kvfree(). Signed-off-by: Denis Efremov <efremov@linux.com> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Diffstat (limited to 'scripts/coccinelle')
-rw-r--r--scripts/coccinelle/api/kzfree.cocci101
1 files changed, 101 insertions, 0 deletions
diff --git a/scripts/coccinelle/api/kzfree.cocci b/scripts/coccinelle/api/kzfree.cocci
new file mode 100644
index 000000000000..33625bd7cec9
--- /dev/null
+++ b/scripts/coccinelle/api/kzfree.cocci
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0-only
+///
+/// Use kzfree, kvfree_sensitive rather than memset or
+/// memzero_explicit followed by kfree
+///
+// Confidence: High
+// Copyright: (C) 2020 Denis Efremov ISPRAS
+// Options: --no-includes --include-headers
+//
+// Keywords: kzfree, kvfree_sensitive
+//
+
+virtual context
+virtual patch
+virtual org
+virtual report
+
+@initialize:python@
+@@
+# kmalloc_oob_in_memset uses memset to explicitly trigger out-of-bounds access
+filter = frozenset(['kmalloc_oob_in_memset', 'kzfree', 'kvfree_sensitive'])
+
+def relevant(p):
+ return not (filter & {el.current_element for el in p})
+
+@cond@
+position ok;
+@@
+
+if (...)
+ \(memset@ok\|memzero_explicit@ok\)(...);
+
+@r depends on !patch forall@
+expression E;
+position p : script:python() { relevant(p) };
+position m != cond.ok;
+type T;
+@@
+
+(
+* memset@m((T)E, 0, ...);
+|
+* memzero_explicit@m((T)E, ...);
+)
+ ... when != E
+ when strict
+* \(kfree\|vfree\|kvfree\)(E)@p;
+
+@rp_memzero depends on patch@
+expression E, size;
+position p : script:python() { relevant(p) };
+position m != cond.ok;
+type T;
+@@
+
+- memzero_explicit@m((T)E, size);
+ ... when != E
+ when strict
+// TODO: uncomment when kfree_sensitive will be merged.
+// Only this case is commented out because developers
+// may not like patches like this since kzfree uses memset
+// internally (not memzero_explicit).
+//(
+//- kfree(E)@p;
+//+ kfree_sensitive(E);
+//|
+- \(vfree\|kvfree\)(E)@p;
++ kvfree_sensitive(E, size);
+//)
+
+@rp_memset depends on patch@
+expression E, size;
+position p : script:python() { relevant(p) };
+position m != cond.ok;
+type T;
+@@
+
+- memset@m((T)E, 0, size);
+ ... when != E
+ when strict
+(
+- kfree(E)@p;
++ kzfree(E);
+|
+- \(vfree\|kvfree\)(E)@p;
++ kvfree_sensitive(E, size);
+)
+
+@script:python depends on report@
+p << r.p;
+@@
+
+coccilib.report.print_report(p[0],
+ "WARNING: opportunity for kzfree/kvfree_sensitive")
+
+@script:python depends on org@
+p << r.p;
+@@
+
+coccilib.org.print_todo(p[0],
+ "WARNING: opportunity for kzfree/kvfree_sensitive")