> From: Stephen Hemminger [mailto:step...@networkplumber.org]
> Sent: Thursday, 13 February 2025 23.16
>
> When memset() is used before a release function such as free,
> the compiler if allowed to optimize the memset away under
> the as-if rules. This is normally ok, but in certain cases such
> as passwords or security keys it is problematic.
>
> Introduce a DPDK wrapper which is equivalent to the
> C23 memset_explicit function.
I agree that zeroing is better than passing the fill character as a parameter.
After switching to zeroing, it's no longer like C23 memset_explicit.
> Name ot the new function chosen to be similar to
Typo: ot -> of
> Linux kernel internal memzero_explicit().
Just merge these last two sentences into one, e.g.:
Introduce a DPDK wrapper which is equivalent to the Linux kernel internal
memzero_explicit().
>
> Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> ---
> lib/eal/include/rte_string_fns.h | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/lib/eal/include/rte_string_fns.h
> b/lib/eal/include/rte_string_fns.h
> index 702bd81251..93aae66614 100644
> --- a/lib/eal/include/rte_string_fns.h
> +++ b/lib/eal/include/rte_string_fns.h
> @@ -15,6 +15,7 @@
> #include <stdio.h>
> #include <string.h>
>
> +#include <rte_atomic.h>
> #include <rte_common.h>
> #include <rte_compat.h>
>
> @@ -149,6 +150,29 @@ rte_str_skip_leading_spaces(const char *src)
> return p;
> }
>
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Fill memory with with zero's (e.g. sensitive keys)
> + * Normally using memset() is fine. But in cases where clearing
> + * out local data before going out of scope or freeing,
> + * use rte_memzero_explicit() to preven the compiler from optimizing
Typo: preven -> prevent
> + * away the zeroing.
> + *
> + * @param dst
> + * target buffer
> + * @param sz
> + * number of bytes to fill
> + */
> +__rte_experimental
> +static inline void
> +rte_memzero_explicit(void *dst, size_t sz)
> +{
> + memset(dst, 0, sz);
> + rte_compiler_barrier();
> +}
> +
> #ifdef __cplusplus
> }
> #endif
> --
> 2.47.2
With description and typos fixed,
Acked-by: Morten Brørup <m...@smartsharesystems.com>
