[PATCH 03/14] ipv6: Annotate struct ip6_sf_socklist with __counted_by

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 ip6_sf_socklist.

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

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <redacted>
---
 include/net/if_inet6.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index c8490729b4ae..3e454c4d7ba6 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h

@@ -89,7 +89,7 @@ struct ip6_sf_socklist {
 	unsigned int		sl_max;
 	unsigned int		sl_count;
 	struct rcu_head		rcu;
-	struct in6_addr		sl_addr[];
+	struct in6_addr		sl_addr[] __counted_by(sl_max);
 };
 
 #define IP6_SFBLOCK	10	/* allocate this many at once */

-- 
2.34.1