[PATCH 02/21] dmaengine: at_hdmac: Annotate struct at_desc with __counted_by

[Kees Cook]

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 at_desc.

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

Cc: Vinod Koul <vkoul@xxxxxxxxxx>
Cc: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: dmaengine@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/dma/at_hdmac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index b2876f67471f..b66c7f416881 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -239,7 +239,7 @@ struct at_desc {
 	bool				memset_buffer;
 	dma_addr_t			memset_paddr;
 	int				*memset_vaddr;
-	struct atdma_sg			sg[];
+	struct atdma_sg			sg[] __counted_by(sglen);
 };
 
 /*--  Channels  --------------------------------------------------------*/
-- 
2.34.1