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 cpuinfo_tree.

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

Cc: "David S. Miller" <da...@davemloft.net>
Cc: sparcli...@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 arch/sparc/kernel/cpumap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c
index f07ea88a83af..8fcf2d8c6bd2 100644
--- a/arch/sparc/kernel/cpumap.c
+++ b/arch/sparc/kernel/cpumap.c
@@ -50,7 +50,7 @@ struct cpuinfo_tree {
 
        /* Offsets into nodes[] for each level of the tree */
        struct cpuinfo_level level[CPUINFO_LVL_MAX];
-       struct cpuinfo_node  nodes[];
+       struct cpuinfo_node  nodes[] __counted_by(total_nodes);
 };
 
 
-- 
2.34.1


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