[PATCH] ACPI: PRM: Annotate struct prm_module_info 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 prm_module_info.

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

Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/acpi/prmt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
index 7020584096bf..c78453c74ef5 100644
--- a/drivers/acpi/prmt.c
+++ b/drivers/acpi/prmt.c
@@ -69,7 +69,7 @@ struct prm_module_info {
 	bool updatable;
 
 	struct list_head module_list;
-	struct prm_handler_info handlers[];
+	struct prm_handler_info handlers[] __counted_by(handler_count);
 };
 
 static u64 efi_pa_va_lookup(u64 pa)
-- 
2.34.1