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 cdns_i3c_xfer.

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

Cc: "Przemysław Gaj" <pgaj@cadence.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: linux-i3c@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/i3c/master/i3c-master-cdns.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c
index 49551db71bc9..97c1010956a0 100644
--- a/drivers/i3c/master/i3c-master-cdns.c
+++ b/drivers/i3c/master/i3c-master-cdns.c
@@ -387,7 +387,7 @@ struct cdns_i3c_xfer {
 	struct completion comp;
 	int ret;
 	unsigned int ncmds;
-	struct cdns_i3c_cmd cmds[];
+	struct cdns_i3c_cmd cmds[] __counted_by(ncmds);
 };
 
 struct cdns_i3c_data {
-- 
2.34.1

On Fri, 22 Sep 2023 10:50:15 -0700, Kees Cook wrote:
> 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 cdns_i3c_xfer.
> 
> [...]

Applied, thanks!

[1/1] i3c: master: cdns: Annotate struct cdns_i3c_xfer with __counted_by
      commit: 49f33846efc079eb94b044bf897e90909fd3aa11

Best regards,

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

On 9/22/23 11:50, Kees Cook wrote:
> 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 cdns_i3c_xfer.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: "Przemysław Gaj" <pgaj@cadence.com>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: linux-i3c@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
-- 
Gustavo

> ---
>   drivers/i3c/master/i3c-master-cdns.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c
> index 49551db71bc9..97c1010956a0 100644
> --- a/drivers/i3c/master/i3c-master-cdns.c
> +++ b/drivers/i3c/master/i3c-master-cdns.c
> @@ -387,7 +387,7 @@ struct cdns_i3c_xfer {
>   	struct completion comp;
>   	int ret;
>   	unsigned int ncmds;
> -	struct cdns_i3c_cmd cmds[];
> +	struct cdns_i3c_cmd cmds[] __counted_by(ncmds);
>   };
>   
>   struct cdns_i3c_data {