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 hwc_dma_buf.

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

Cc: Long Li <longli@microsoft.com>
Cc: Ajay Sharma <redacted>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
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: linux-rdma@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <redacted>
---
 include/net/mana/hw_channel.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/mana/hw_channel.h b/include/net/mana/hw_channel.h
index 3d3b5c881bc1..158b125692c2 100644
--- a/include/net/mana/hw_channel.h
+++ b/include/net/mana/hw_channel.h

@@ -121,7 +121,7 @@ struct hwc_dma_buf {
 	u32 gpa_mkey;
 
 	u32 num_reqs;
-	struct hwc_work_request reqs[];
+	struct hwc_work_request reqs[] __counted_by(num_reqs);
 };
 
 typedef void hwc_rx_event_handler_t(void *ctx, u32 gdma_rxq_id,

-- 
2.34.1