RE: [PATCH] regulator: da9063: Replace zero-length array with flexible-array member

From: Adam Thomson
Date: Wed Feb 12 2020 - 06:14:49 EST


On 11 February 2020 23:47, Gustavo A. R. Silva wrote:

> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertenly introduced[3] to the codebase from now on.
>
> This issue was found with the help of Coccinelle.
>
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
> drivers/regulator/da9063-regulator.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/regulator/da9063-regulator.c b/drivers/regulator/da9063-
> regulator.c
> index 2b0c7a85306a..368f8ad2a9f9 100644
> --- a/drivers/regulator/da9063-regulator.c
> +++ b/drivers/regulator/da9063-regulator.c
> @@ -119,7 +119,7 @@ struct da9063_regulator {
> struct da9063_regulators {
> unsigned n_regulators;
> /* Array size to be defined during init. Keep at end. */
> - struct da9063_regulator regulator[0];
> + struct da9063_regulator regulator[];

Same comment as for da9062. The probe uses malloc and does not statically
initialise for this struct so this will break the probe.

> };
>
> /* BUCK modes for DA9063 */
> --
> 2.25.0