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 gcov_iterator.

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

Cc: Peter Oberparleiter <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
---
 kernel/gcov/fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/gcov/fs.c b/kernel/gcov/fs.c
index 5c3086cad8f9..01520689b57c 100644
--- a/kernel/gcov/fs.c
+++ b/kernel/gcov/fs.c
@@ -99,7 +99,7 @@ struct gcov_iterator {
        struct gcov_info *info;
        size_t size;
        loff_t pos;
-       char buffer[];
+       char buffer[] __counted_by(size);
 };
 
 /**
-- 
2.34.1


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