On Wednesday, August 17, 2016 2:42:11 PM CEST Kees Cook wrote:
> +
> +/*
> + * Since detected data corruption should stop operation on the affected
> + * structures, this returns false if the corruption condition is found.
> + */
> +#define CHECK_DATA_CORRUPTION(condition, fmt, ...)                      \
> +       do {                                                             \
> +               if (unlikely(condition)) {                               \
> +                       if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \
> +                               pr_err(fmt, ##__VA_ARGS__);              \
> +                               BUG();                                   \
> +                       } else                                           \
> +                               WARN(1, fmt, ##__VA_ARGS__);             \
> +                       return false;                                    \
> +               }                                                        \
> +       } while (0)
> +

I think the "return false" inside of the macro makes it easy to misread
what is actually going on.

How about making it a macro that returns the condition argument?

#define CHECK_DATA_CORRUPTION(condition, fmt, ...)      \
({      \
        bool _condition = unlikely(condition);  \
        if (_condition) {       \
                ...
        }       \
        _condition;     \
})

        Arnd

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