[PATCH 21/21] dmaengine: usb-dmac: Annotate struct usb_dmac_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 usb_dmac_desc.

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

Cc: Vinod Koul <vkoul@xxxxxxxxxx>
Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
Cc: dmaengine@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/dma/sh/usb-dmac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
index b14cf350b669..4cfcd23e3268 100644
--- a/drivers/dma/sh/usb-dmac.c
+++ b/drivers/dma/sh/usb-dmac.c
@@ -57,7 +57,7 @@ struct usb_dmac_desc {
 	u32 residue;
 	struct list_head node;
 	dma_cookie_t done_cookie;
-	struct usb_dmac_sg sg[];
+	struct usb_dmac_sg sg[] __counted_by(sg_allocated_len);
 };
 
 #define to_usb_dmac_desc(vd)	container_of(vd, struct usb_dmac_desc, vd)
-- 
2.34.1