[PATCH] irqdomain: Annotate struct irq_domain with __counted_by

[Kees Cook]

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct irq_domain.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 include/linux/irqdomain.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 51c254b7fec2..ee0a82c60508 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -174,7 +174,7 @@ struct irq_domain {
 	irq_hw_number_t			hwirq_max;
 	unsigned int			revmap_size;
 	struct radix_tree_root		revmap_tree;
-	struct irq_data __rcu		*revmap[];
+	struct irq_data __rcu		*revmap[] __counted_by(revmap_size);
 };
 
 /* Irq domain flags */
-- 
2.34.1