Re: [RFC PATCH] crypto: flush poison data

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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@xxxxxxxxxxxx>
---

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

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