Re: [PATCH 5.4 regression fix] x86/boot: Provide memzero_explicit
From: Stephan Mueller
Date: Mon Oct 07 2019 - 05:02:28 EST
Am Montag, 7. Oktober 2019, 10:55:01 CEST schrieb Hans de Goede:
Hi Hans,
> The purgatory code now uses the shared lib/crypto/sha256.c sha256
> implementation. This needs memzero_explicit, implement this.
>
> Reported-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
> Fixes: 906a4bb97f5d ("crypto: sha256 - Use get/put_unaligned_be32 to get
> input, memzero_explicit") Signed-off-by: Hans de Goede
> <hdegoede@xxxxxxxxxx>
> ---
> arch/x86/boot/compressed/string.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/string.c
> b/arch/x86/boot/compressed/string.c index 81fc1eaa3229..511332e279fe 100644
> --- a/arch/x86/boot/compressed/string.c
> +++ b/arch/x86/boot/compressed/string.c
> @@ -50,6 +50,11 @@ void *memset(void *s, int c, size_t n)
> return s;
> }
>
> +void memzero_explicit(void *s, size_t count)
> +{
> + memset(s, 0, count);
May I ask how it is guaranteed that this memset is not optimized out by the
compiler, e.g. for stack variables?
> +}
> +
> void *memmove(void *dest, const void *src, size_t n)
> {
> unsigned char *d = dest;
Ciao
Stephan