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

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922172858.3822653-3-keescook@chromium.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index c8490729b4aea7949254f6c991eb8ca61a35a598..3e454c4d7ba623d6abcfcfb396c0f4390de84c5a 100644 (file)
--- 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 */