[PATCH 2/5] Add explicit_bzero()

[Sebastian Huber]

Ok, I should have added this to the commit message. The current version 
is not link-time optimization safe. See discussions:

https://gcc.gnu.org/ml/gcc-help/2016-02/msg00042.html

https://gcc.gnu.org/ml/gcc/2015-09/msg00135.html

My conclusion was to wait for proper compiler support.

On 18/03/16 12:24, Corinna Vinschen wrote:
> On Mar 18 11:49, Sebastian Huber wrote:
>> This function is used by LibreSSL and OpenSSH and is provided by the
>> OpenBSD libc.
>> [...]
>> +#include <string.h>
>> +
>> +/*
>> + * explicit_bzero - don't let the compiler optimize away bzero
>> + */
>> +void
>> +explicit_bzero(void *p, size_t n)
>> +{
>> +	bzero(p, n);
>> +}
> The OpenSSH version looks a bit different:
>
>    /*
>     * Indirect bzero through a volatile pointer to hopefully avoid
>     * dead-store optimisation eliminating the call.
>     */
>    static void (* volatile ssh_bzero)(void *, size_t) = bzero;
>
>    void
>    explicit_bzero(void *p, size_t n)
>    {
> 	  ssh_bzero(p, n);
>    }
>
> Is that something we should do, too, or is that paranoia at its
> finest only?
>
>
> Thanks,
> Corinna
>

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Sebastian Huber, embedded brains GmbH

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