crypto: asym_tpm: correct zero out potential secrets

The function derive_pub_key() should be calling memzero_explicit()
instead of memset() in case the complier decides to optimize away the
call to memset() because it "knows" no one is going to touch the memory
anymore.

Cc: stable <[email protected]>
Reported-by: Ilil Blum Shem-Tov <[email protected]>
Tested-by: Ilil Blum Shem-Tov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: gregkh

crypto/asymmetric_keys/asym_tpm.c

@@ -354,7 +354,7 @@ static uint32_t derive_pub_key(const void *pub_key, uint32_t len, uint8_t *buf)
 	memcpy(cur, e, sizeof(e));
 	cur += sizeof(e);
 	/* Zero parameters to satisfy set_pub_key ABI. */
-	memset(cur, 0, SETKEY_PARAMS_SIZE);
+	memzero_explicit(cur, SETKEY_PARAMS_SIZE);
 
 	return cur - buf;
 }