Re: [RFC PATCH] crypto: flush poison data

Ben Dooks
2022-07-01T14:09:07Z

On 01/07/2022 14:27, Corentin Labbe wrote:
> On my Allwinner D1 nezha, the sun8i-ce fail self-tests due to:
> alg: skcipher: cbc-des3-sun8i-ce encryption overran dst buffer on test vector 0
>
> In fact the buffer is not overran by device but by the dma_map_single() operation.
>
> To prevent any corruption of the poisoned data, simply flush them before
> giving the buffer to the tested driver.
>
> Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
> ---
>
> Hello
>
> I put this patch as RFC, since this behavour happen only on non yet merged RISCV code.
> (Mostly riscv: implement Zicbom-based CMO instructions + the t-head variant)
>
> Regards
>
> crypto/testmgr.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index c59bd9e07978..187163e2e593 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -19,6 +19,7 @@
> #include <crypto/aead.h>
> #include <crypto/hash.h>
> #include <crypto/skcipher.h>
> +#include <linux/cacheflush.h>
> #include <linux/err.h>
> #include <linux/fips.h>
> #include <linux/module.h>
> @@ -205,6 +206,8 @@ static void testmgr_free_buf(char *buf[XBUFSIZE])
> static inline void testmgr_poison(void *addr, size_t len)
> {
> memset(addr, TESTMGR_POISON_BYTE, len);
> + /* Be sure data is written to prevent corruption from some DMA sync */
> + flush_icache_range((unsigned long)addr, (unsigned long)addr + len);
> }
>
> /* Is the memory region still fully poisoned? */

why are you flushing the instruction cache and not the data-cache?

--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius