On 9/22/23 11:28, Kees Cook wrote:
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" <da...@davemloft.net>
Cc: Eric Dumazet <eduma...@google.com>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: Paolo Abeni <pab...@redhat.com>
Cc: net...@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavo...@kernel.org>

Thanks
--
Gustavo

---
  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 */

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