Re: [PATCH v2 01/10] kdbus: fix operator precedence issues in item macros

[David Herrmann]

Hi

On Tue, Jun 9, 2015 at 10:59 PM, Sergei Zviagintsev <sergei@xxxxxxxx> wrote:
> `_i' argument in KDBUS_ITEM_NEXT and KDBUS_ITEMS_END macros is not
> enclosed into parentheses when the cast operator is applied, which
> leads to improper type conversion if `_i' is supplied as a complex
> expression, e.g.
>
>     KDBUS_ITEM_NEXT(condition ? a : b)
>
> KDBUS_ITEMS_SIZE macro has similar issue, missing parentheses around
> `_h' when using indirection operator.
>
> Use parentheses properly to guarantee right precedence.
>
> Signed-off-by: Sergei Zviagintsev <sergei@xxxxxxxx>
> ---
>  ipc/kdbus/item.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: David Herrmann <dh.herrmann@xxxxxxxxx>

Thanks
David

> diff --git a/ipc/kdbus/item.h b/ipc/kdbus/item.h
> index eeefd8beac3b..32909e2e7954 100644
> --- a/ipc/kdbus/item.h
> +++ b/ipc/kdbus/item.h
> @@ -21,8 +21,8 @@
>  #include "util.h"
>
>  /* generic access and iterators over a stream of items */
> -#define KDBUS_ITEM_NEXT(_i) (typeof(_i))(((u8 *)_i) + KDBUS_ALIGN8((_i)->size))
> -#define KDBUS_ITEMS_SIZE(_h, _is) ((_h)->size - offsetof(typeof(*_h), _is))
> +#define KDBUS_ITEM_NEXT(_i) (typeof(_i))((u8 *)(_i) + KDBUS_ALIGN8((_i)->size))
> +#define KDBUS_ITEMS_SIZE(_h, _is) ((_h)->size - offsetof(typeof(*(_h)), _is))
>  #define KDBUS_ITEM_HEADER_SIZE offsetof(struct kdbus_item, data)
>  #define KDBUS_ITEM_SIZE(_s) KDBUS_ALIGN8(KDBUS_ITEM_HEADER_SIZE + (_s))
>  #define KDBUS_ITEM_PAYLOAD_SIZE(_i) ((_i)->size - KDBUS_ITEM_HEADER_SIZE)
> @@ -40,7 +40,7 @@
>          (u8 *)(_i) >= (u8 *)(_is))
>
>  #define KDBUS_ITEMS_END(_i, _is, _s)                                   \
> -       ((u8 *)_i == ((u8 *)(_is) + KDBUS_ALIGN8(_s)))
> +       ((u8 *)(_i) == ((u8 *)(_is) + KDBUS_ALIGN8(_s)))
>
>  /**
>   * struct kdbus_item_header - Describes the fix part of an item
> --
> 1.8.3.1
>
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