[PATCH] audit: Annotate struct audit_chunk 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 audit_chunk.

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

Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Cc: audit@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 kernel/audit_tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index e867c17d3f84..85a5b306733b 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -34,7 +34,7 @@ struct audit_chunk {
 		struct list_head list;
 		struct audit_tree *owner;
 		unsigned index;		/* index; upper bit indicates 'will prune' */
-	} owners[];
+	} owners[] __counted_by(count);
 };
 
 struct audit_tree_mark {
-- 
2.34.1