[cocci] [PATCH v3] scripts/coccinelle: Add script for using ARRAY_END()

Recently, we added an ARRAY_END() macro to simplify finding a pointer
one past the last element in an array.  Such a pointer is often called
the 'end', and thus the macro name.

Make it easy to find more places where that macro should be used.

See also:
436debc9cad8 ("array_size.h: add ARRAY_END()")
8118f197b7b7 ("mm: fix benign off-by-one bugs")
a9e5620c9a9e ("kernel: fix off-by-one benign bugs")
61e9210e2392 ("mm: use ARRAY_END() instead of open-coding it")

Cc: Kees Cook <[email protected]>
Cc: Markus Elfring <[email protected]>
Cc: Julia Lawall <[email protected]>
Cc: Nicolas Palix <[email protected]>
Signed-off-by: Alejandro Colomar <[email protected]>
---

Hi!

This v3 only has one change: I've removed the comment about the false
negatives.  They were due to spatch(1) not being able to correctly parse
unrelated code elsewhere.

See range-diff and interdiff at the bottom.


Have a lovely night!
Alex

 scripts/coccinelle/misc/array_end.cocci | 73 +++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 scripts/coccinelle/misc/array_end.cocci

diff --git a/scripts/coccinelle/misc/array_end.cocci b/scripts/coccinelle/misc/array_end.cocci
new file mode 100644
index 00000000..88c664de
--- /dev/null
+++ b/scripts/coccinelle/misc/array_end.cocci
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/// Use ARRAY_END instead of an expression derived from ARRAY_SIZE
+//
+// Confidence: High
+// Copyright: 2026, Alejandro Colomar <[email protected]>
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+@depends on context@
+type T;
+T[] a;
+expression b;
+@@
+(
+* (a + ARRAY_SIZE(a))
+|
+* (&a[0] + ARRAY_SIZE(a))
+|
+* (&a[ARRAY_SIZE(a)])
+|
+* (&a[ARRAY_SIZE(a) - b])
+)
+
+@depends on patch@
+type T;
+T[] a;
+expression b;
+@@
+(
+- (a + ARRAY_SIZE(a))
++ ARRAY_END(a)
+|
+- (&a[0] + ARRAY_SIZE(a))
++ ARRAY_END(a)
+|
+- (&a[ARRAY_SIZE(a)])
++ ARRAY_END(a)
+|
+- (&a[ARRAY_SIZE(a) - b])
++ ARRAY_END(a) - b
+)
+
+@r depends on org || report@
+type T;
+T[] a;
+expression b;
+position p;
+@@
+(
+ (a@p + ARRAY_SIZE(a))
+|
+ (&a[0]@p + ARRAY_SIZE(a))
+|
+ (&a[ARRAY_SIZE(a)]@p)
+|
+ (&a[ARRAY_SIZE(a)@p - b])
+)
+
+@script:python depends on org@
+p << r.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING should use ARRAY_END")
+
+@script:python depends on report@
+p << r.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING: opportunity for ARRAY_END")

Range-diff:
1:  9fd8d3d1 ! 1:  2ae22f8b scripts/coccinelle: Add script for using ARRAY_END()
    @@ scripts/coccinelle/misc/array_end.cocci (new)
     +//
     +// Confidence: High
     +// Copyright: 2026, Alejandro Colomar <[email protected]>
    -+// Comments: No known false positives, but has a few false negatives
     +// Options: --no-includes --include-headers
     +
     +virtual patch
-- 
2.53.0