flow_offload: Annotate struct flow_action_entry 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 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 flow_action_entry.

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
Link: 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>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
index 9efa9a59e81f67a0acb95e63c6e948abb3bda8b4..314087a5e18183e19e6be85d4d238b46aafce738 100644 (file)
--- a/include/net/flow_offload.h
+++ b/include/net/flow_offload.h
@@ -333,7 +333,7 @@ struct flow_action_entry {
 
 struct flow_action {
        unsigned int                    num_entries;
-       struct flow_action_entry        entries[];
+       struct flow_action_entry        entries[] __counted_by(num_entries);
 };
 
 static inline bool flow_action_has_entries(const struct flow_action *action)