[PATCH] i3c: dw: Annotate struct dw_i3c_xfer with __counted_by

[PATCH] i3c: dw: Annotate struct dw_i3c_xfer 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 dw_i3c_xfer.

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

Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Joel Stanley <joel@jms.id.au>
Cc: linux-i3c@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/i3c/master/dw-i3c-master.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index 9332ae5f6419..ef5751e91cc9 100644
--- a/drivers/i3c/master/dw-i3c-master.c
+++ b/drivers/i3c/master/dw-i3c-master.c
@@ -233,7 +233,7 @@ struct dw_i3c_xfer {
 	struct completion comp;
 	int ret;
 	unsigned int ncmds;
-	struct dw_i3c_cmd cmds[];
+	struct dw_i3c_cmd cmds[] __counted_by(ncmds);
 };
 
 struct dw_i3c_i2c_dev_data {
-- 
2.34.1

Re: [PATCH] i3c: dw: Annotate struct dw_i3c_xfer with __counted_by

[Jeremy Kerr]

Hi Kees,

> 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).

Nice!

Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>

Cheers,


Jeremy

Re: [PATCH] i3c: dw: Annotate struct dw_i3c_xfer with __counted_by

[Gustavo A. R. Silva]

On Fri, Sep 22, 2023 at 10:50:11AM -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 dw_i3c_xfer.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Jeremy Kerr <jk@codeconstruct.com.au>
> Cc: Joel Stanley <joel@jms.id.au>
> 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/dw-i3c-master.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
> index 9332ae5f6419..ef5751e91cc9 100644
> --- a/drivers/i3c/master/dw-i3c-master.c
> +++ b/drivers/i3c/master/dw-i3c-master.c
> @@ -233,7 +233,7 @@ struct dw_i3c_xfer {
>  	struct completion comp;
>  	int ret;
>  	unsigned int ncmds;
> -	struct dw_i3c_cmd cmds[];
> +	struct dw_i3c_cmd cmds[] __counted_by(ncmds);
>  };
>  
>  struct dw_i3c_i2c_dev_data {
> -- 
> 2.34.1
> 
> 

Re: [PATCH] i3c: dw: Annotate struct dw_i3c_xfer with __counted_by

[Alexandre Belloni]

On Fri, 22 Sep 2023 10:50:11 -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 dw_i3c_xfer.
> 
> [...]

Applied, thanks!

[1/1] i3c: dw: Annotate struct dw_i3c_xfer with __counted_by
      commit: 014c9a0e6f9ff573099051e1e2ff6efc3470d02d

Best regards,

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